Internet DRAFT - draft-foster-e164-gstn-np

draft-foster-e164-gstn-np





                                                            Mark Foster 
Internet Draft                                              Tom McGarry 
Document: <draft-foster-e164-gstn-np-00.txt>                   James Yu 
                                                          NeuStar, Inc. 
Category: Informational                                      March 2000 
 
 
              Number Portability in the GSTN: An Overview 
 
 
Status of this Memo 
 
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026 [RFC].  
 
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1. Abstract 
    
   This document provides an overview of E.164 telephone number 
   portability (NP) in the Global Switched Telephone Network (GSTN).  
   There are three types of number portability: service provider 
   portability (SPNP), location portability, and service portability.  
   Service provider portability, the focus of the present draft, is a 
   regulatory imperative in many countries seeking to liberalize local 
   telephony service competition, by enabling end-users to retain pre-
   existing telephone numbers while changing service providers.  
   Implementation of NP within national GSTN entails potentially 
   significant changes to numbering administration, network element 
   signaling, call routing and processing, billing, service management, 
   and other functions.  NP changes the fundamental nature of a dialed 
   E.164 number from a hierarchical physical routing address to a 
   virtual address, thereby requiring the transparent translation of 
   the later to the former.  In addition, there are various regulatory 

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   constraints which establish relevant parameters for NP 
   implementation, most of which are not network technology specific.  
   Consequently, the implementation of NP behavior consistent with 
   applicable regulatory constraints, as well as the need for 
   interoperation with the existing GSTN NP implementations, are  
   relevant topics for numerous areas of IP telephony work-in-progress 
   at IETF. 
 
    
2. Introduction 
    
   This document provides an overview of E.164 telephone number 
   portability in the Global Switched Telephone Network (GSTN).  There 
   are considered to be three types of number portability (NP): service 
   provider portability (SPNP), location portability (not to be 
   confused with terminal mobility), and service portability. 
    
   Service number provider portability (SPNP), the focus of the present 
   draft, is a regulatory imperative in many countries seeking to 
   liberalize telephony service competition, especially local service.  
   Historically, local telephony service (as compared to long distance 
   or international) has been regulated as a utility-like form of 
   service.  While a number of countries had begun liberalization (e.g. 
   privatization, de-regulation, or re-regulation) some years ago, the 
   advent of NP is relatively recent (since ~1995). 
    
   E.164 numbers were intentionally designed as hierarchical routing 
   addresses which could systematically be digit-analyzed to ascertain 
   the country, serving network provider, serving end-office switch, 
   and specific line of the called party.  As such, without NP a 
   subscriber wishing to change service providers would incur a number 
   change as a consequence of being served off of a different end-
   office switch operated by the new service provider.  The cost and 
   convenience impact to the subscriber of changing numbers is seen as 
   barrier to competition.  Hence NP has become associated with GSTN 
   infrastructure enhancements associated with a competitive 
   environment driven by regulatory directives. 
    
   Forms of SPNP have been deployed or are being deployed widely in the 
   GSTN in various parts of the world, including the US, Canada, 
   Western Europe, Australia, and the Pacific Rim (e.g. Hong Kong). 
   Other regions, such as South America (e.g. Brazil) are actively 
   considering it. 
    
   Implementation of NP within a national telephony infrastructure 
   entails potentially significant changes to numbering administration, 
   network element signaling, call routing and processing, billing, 
   service management, and other functions. 
    
   NP changes the fundamental nature of a dialed E.164 number from a 
   hierarchical physical routing address to a virtual address.  NP 
   implementations attempt to encapsulate the impacts to the GSTN and 
   make NP transparent to subscribers by incorporating a translation 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   function to map a dialed, potentially ported E.164 address, into a 
   network routing address (either a number prefix or another E.164 
   address) which can be hierarchically routed. 
    
   This is roughly analogous to the use of network address translation 
   on IP addresses to enable IP address portability by containing the 
   impact of the address change to the edge of the network and retain 
   the use of CIDR blocks in the core which can be route aggregated by 
   the network service provider to the rest of the internet. 
    
   NP bifurcates the historical role of a subscriberĂs E.164 address 
   into two or more data elements (a dialed or virtual address, and a 
   network routing address) that must be made available to network 
   elements through an NP translations database, carried by forward 
   call signaling, and recorded on call detail records.  Not only is 
   call processing and routing affected, but so is SS7/C7 messaging.  A 
   number of TCAP-based SS7 messaging sets utilize an E.164 address as 
   an application-level network element address in the global title 
   address field (GTA) field of the SCCP message header.  Consequently, 
   SS7/C7 signaling transfer points (STPs) and gateways need to be able 
   to perform n-digit global title translation (GTT) to translate a 
   dialed E.164 address into its network address counterpart via the NP 
   database. 
    
   In addition, there are various national regulatory constraints which 
   establish relevant parameters for NP implementation, most of which 
   are not network technology specific.  Consequently, implementations 
   of NP behavior in IP telephony consistent with applicable regulatory 
   constraints, as well as the need for interoperation with the 
   existing GSTN NP implementations, are relevant topics for numerous 
   areas of IP telephony work-in-progress at IETF. 
    
   This document describes three types of number portability and the 
   four schemes that have been standardized to support SPNP 
   specifically.  Following that, specific information regarding the 
   call routing and database query implementations are described for 
   several regions (North American and Europe) and industries (wireless 
   vs. wireline). The Number Portability Database (NPDB) interfaces and 
   the call routing schemes that are used in the North America and 
   Europe are described to show the variety of standards that may be 
   implemented worldwide.  Number pooling is briefly discussed to show 
   how NP is being enhanced in the US to conserve North American area 
   codes.  The conclusion briefly touches the potential impacts of NP 
   on IP & Telecommunications Interoperability.  Appendix A provides 
   some specific technical and regulatory information on NP in North 
   America.  Appendix B describes the number portability administration 
   process that manages the number portability database in North 
   America. 
    
    
3. Abbreviations and Acronyms 
    
   ACQ     All Call Query 
  
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   AMPS    Advanced Mobile Phone System 
   ANSI    American National Standards Institute 
   CDMA    Code Division Multiple Access 
   CdPA    Called Party Address 
   CdPN    Called Party Number 
   CH      Code Holder 
   CMIP    Common Management Information Protocol 
   CRTC    Canadian Radio and Television Commission 
   CS1     Capability Set 1 
   CS2     Capability Set 2 
   DN      Directory Number 
   ETSI    European Technical Standards Institute 
   FCC     Federal Communications Commission 
   FCI     Forward Call Indicator 
   GAP     Generic Address Parameter 
   GMSC    Gateway Mobile Services Switching Center 
   GSM     Global System for Mobile Communications 
   GSTN    Global Switched Telephone Network 
   GW      Gateways 
   HLR     Home Location Register 
   IAM     Initial Address Message 
   ICC     Illinois Commerce Commission 
   IN      Intelligent Network 
   INAP    Intelligent Network Application Part 
   IP      Internet Protocol 
   IS-41   Interim Standards Number 41 
   ITN     Individual Telephony Number  
   ITU     International Telecommunication Union 
   ITU-TS  ITU-Telecommunication Sector 
   ISUP    ISDN User Part 
   ISDN    Integrated Services Digital Network 
   LEC     Local Exchange Carrier 
   LLC     Limited Liability Corporation 
   LNP     Local Number Portability 
   LRN     Location Routing Number 
   LSMS    Local Service Management System 
   MAP     Mobile Application Part 
   MNP     Mobile Number Portability 
   MSRN    Mobile Station Roaming Number 
   MTP     Message Transfer Part 
   NANC    North American Numbering Council 
   NANP    North American Numbering Plan 
   NP      Number Portability 
   NPAC    Number Portability Administration Center 
   NPDB    Number Portability Database 
   NPRM    Notice of Proposed Rulemaking 
   NRN     Network Routing Number 
   OR      Onward Routing 
   PCS     Personal Communication Services 
   PUC     Public Utility Commission 
   QoR     Query on Release 
   RBOC    Regional Bell Operating Company 
   RN      Routing Number 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   RTP     Return to Pivot 
   SCCP    Signaling Connection Control Part 
   SMS     Service Management System 
   SOA     Service Order Administration 
   SRF     Signaling Relaying Function 
   SRI     Send Routing Information 
   SS7     Signaling System Number 7 
   TCAP    Transaction Capabilities Application Part 
   TCNI    Translated Called Number Indicator 
   TDMA    Time Division Multiple Access 
   TN      Telephone Number 
    
    
4. Types of Number Portability 
    
   As there are several types of E.164 numbers (telephone numbers, or 
   just TN) in the GSTN, there are correspondingly several types of 
   E.164 NP in the GSTN.  First there are so-call non-geographic E.164 
   numbers, commonly used for service specific applications such as 
   freephone (800 or 0800).  Portability of these are call non-
   geographic number portability (NGNP).  NGNP, for example, was 
   deployed in the US in 1986-92. 
    
   Geographic number portability, which includes traditional fixed or 
   wireline numbers as well as mobile numbers which are allocated out 
   of geographic number range prefixes, is called NP or in the US local 
   number portability (LNP). 
    
   Number portability allows the telephony subscribers in the Global 
   Switched Telephone Network (GSTN) to keep their phone numbers when 
   they change their service providers or subscribed services, or when 
   they move to new to a new location.   
    
   The ability to change the service provider while keeping the same 
   phone number is called service provider portability (SPNP) also 
   known as "operator portability." 
    
   The ability to change the subscriberĂs fixed service location while 
   keeping the same phone number is called location portability. 
    
   The ability to change the subscribed services (e.g., from the plain 
   old telephone service to Integrated Services Digital Network (ISDN) 
   services) while keeping the same phone number is called service 
   portability.  Another aspect of service portability is to allow the 
   subscribers to enjoy the subscribed services in the same way when 
   they roam outside their home networks, also known as single number 
   services. 
    
   In addition, mobile number portability (MNP) refers to specific NP 
   implementation in mobile networks either as part of a broader NP 
   implementation in the GSTN or on a stand-alone basis.  Where 
   interoperation of LNP and MNP is supported, service portability 
   between fixed and mobile service types is possible. 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
    
   At present, SPNP has been the primary form of NP deployed due to its 
   relevance in enabling local service competition. 
    
   Also in use in the GSTN are the terms interim NP (INP or ILNP) and 
   true NP.  Interim NP usually refers to the use of remote call 
   forwarding-like measures to forward calls to ported numbers through 
   the donor network to the new service network.  These are considered 
   interim relative to true NP, which seeks to remove the donor network 
   or old service provider from the call or signaling path altogether.  
   Often the distinction between interim and true NP is a national 
   regulatory matter relative to the technical/operational requirements 
   imposed on NP in that country. 
    
   Implementations of true NP in certain countries (e.g. US, Canada, 
   Spain, Belgium, Denmark) may pose specific requirements for IP 
   telephony implementations as a result of regulatory and industry 
   requirements for providing call routing and signaling independent of 
   the donor network or last previous serving network. 
    
    
5. Service Provider Number Portability Schemes 
    
   Four schemes can be used to support service provider portability and 
   are briefly described below.  But first, some further terms are 
   introduced. 
    
   The donor network is the network that first assigned a telephone 
   number (e.g., TN +1 202-533-1234) to a subscriber, out of a number 
   range administratively (e.g., +1 202-533) assigned to it.  The old 
   serving network (or old SP) is the network that previously served 
   the ported number before the number ported to another network, 
   called the new serving network or current service provider (SP).  
   The new service provider (new SP) or current serving network is the 
   network that currently serves the ported number. 
    
   Since a TN can port a number of times, the old SP is not necessarily 
   the same as the donor network, except for the first time the TN 
   ports away, or if the TN ports back into the donor network and away 
   again.  While the new SP and old SP roles are transitory as a TN 
   ports around, the donor network is always the same for any 
   particular TN based on the service provider to whom the subtending 
   number range was administratively assigned.  See the discussion 
   below on number pooling, as this enhancement to NP further 
   bifurcates the role of donor network into two (the number range or 
   code holder network, and the block holder network). 
    
   To simplify the illustration, all the transit networks are ignored, 
   the originating or donor network is the one that performs the 
   database queries or call redirection, and the dialed directory 
   number (TN) has been ported out of the donor network before.  
    

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   It is assumed that the old serving network, the new serving network 
   and the donor network are different networks so as to show which 
   networks are involved in call handling and routing and database 
   queries in each of four schemes.  Please note that the port of the 
   number (process of moving it from one network to another) happened 
   prior to the call setup and is not included in the call steps.  
   Information carried in the signaling messages to support each of the 
   four schemes is not discussed to simplify the explanation. 
    
    
5.1 All Call Query (ACQ) 
    
   Figure 1 shows the call steps for the ACQ scheme.  Those call steps 
   are as follows: 
    
   (1) The Originating Network receives a call from the caller and 
       sends a query to a centrally administered Number Portability 
       Database (NPDB), a copy of which is usually resident on a 
       network element within its network or through a third party 
       provider. 
   (2) The NPDB returns the routing number associated with the dialed 
       directory number.  The routing number is discussed later in 
       Section 7. 
   (3) The Originating Network uses the routing number to route the 
       call to the new serving network. 
    
    
    
   +-------------+              +-----------+    Number   +-----------+ 
   | Centralized |              | New Serv. |    ported   | Old Serv. | 
   |    NPDB     |    +-------->|  Network  |<------------|  Network  | 
   +-------------+    |         +-----------+             +-----------+ 
       ^  |           | 
       |  |           | 
      1|  |         3.| 
       |  | 2.        | 
       |  |           | 
       |  v          | 
    +----------+      |         +----------+           +----------+ 
    |   Orig.  |------+         |   Donor  |           | Internal | 
    |  Network |                |  Network |           |   NPDB   | 
    +----------+                +----------+           +----------+ 
    
    
              Figure 1 - All Call Query (ACQ) Scheme. 
 
    
5.2 Query on Release (QoR) 
 
  Figure 2 shows the call steps for the QoR scheme.  Those call steps 
  are as follows: 
    

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   (1) The Originating Network receives a call from the caller and 
       routes the call to the donor network. 
   (2) The donor network releases the call and indicates that the 
       dialed directory number has been ported out of that switch. 
   (3) The Originating Network sends a query to its copy of the 
       centrally administered NPDB. 
   (4) The NPDB returns the routing number associated with the dialed 
       directory number.   
   (5) The Originating Network uses the routing number to route the 
       call to new serving network. 
    
    
   +-------------+              +-----------+    Number   +-----------+ 
   | Centralized |              | New Serv. |    ported   | Old Serv. | 
   |    NPDB     |              |  Network  |<------------|  Network  | 
   +-------------+              +-----------+             +-----------+ 
       ^  |                          ^ 
       |  | 4.                       | 
     3.|  |              5.          | 
       |  |   +----------------------+ 
       |  |   | 
       |  v   | 
    +----------+      2.        +----------+           +----------+ 
    |   Orig.  |<---------------|   Donor  |           | Internal | 
    |  Network |--------------->|  Network |           |   NPDB   | 
    +----------+      1.        +----------+           +----------+ 
    
                   
                Figure 2 - Query on Release (QoS) Scheme. 
    
    
5.3 Call Dropback 
    
  Figure 3 shows the call steps for the Dropback scheme.  This scheme 
  is also known as "Return to Pivot (RTP)."  Those call steps are as 
  follows: 
    
   (1) The Originating Network receives a call from the caller and 
       routes the call to the donor network. 
   (2) The donor network detects that the dialed directory number has 
       been ported out of the donor switch and checks with an internal 
       network-specific NPDB.  
   (3) The internal NPDB returns the routing number associated with the 
       dialed directory number. 
   (4) The donor network releases the call by providing the routing 
       number. 
   (5) The Originating Network uses the routing number to route the 
       call to the new serving network. 
    
    
   +-------------+              +-----------+    Number   +-----------+ 
   | Centralized |              | New Serv. |    porting  | Old Serv. | 
   |    NPDB     |              |  Network  |<------------|  Network  | 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   +-------------+              +-----------+             +-----------+ 
                                    /\ 
                                     | 
                           5.        | 
            +------------------------+ 
            | 
            | 
    +----------+       4.       +----------+     3.    +----------+ 
    |   Orig.  |<---------------|   Donor  |<----------| Internal | 
    |  Network |--------------->|  Network |---------->|   NPDB   | 
    +----------+      1.        +----------+    2.     +----------+ 
    
                   
                      Figure 3 - Dropback Scheme. 
    
    
5.4 Onward Routing (OR) 
    
  Figure 4 shows the call steps for the Dropback scheme.  This scheme 
  is also called Remote Call Forwarding.  Those call steps are as 
  follows: 
    
   (1) The Originating Network receives a call from the caller and 
       routes the call to the donor network. 
   (2) The donor network detects that the dialed directory number has 
       been ported out of the donor switch and checks with an internal 
       network-specific NPDB.  
   (3) The internal NPDB returns the routing number associated with the 
       dialed directory number. 
   (4) The donor network uses the routing number to route the call to 
       the new serving network. 
    
    
   +-------------+              +-----------+    Number   +-----------+ 
   | Centralized |              | New Serv. |    porting  | Old Serv. | 
   |    NPDB     |              |  Network  |<------------|  Network  | 
   +-------------+              +-----------+             +-----------+ 
                                    /\ 
                                     | 
                                   4.| 
                                     | 
                                     | 
                                     | 
    +----------+                +----------+     3.    +----------+ 
    |   Orig.  |                |   Donor  |<----------| Internal | 
    |  Network |--------------->|  Network |---------->|   NPDB   | 
    +----------+      1.        +----------+    2.     +----------+ 
    
                   
                 Figure 4 - Onward Routing (OR) Scheme. 
    
    
5.5 Comparisons of the Four Schemes 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
    
   Only the ACQ scheme does not involve the donor network when routing 
   the call to the new serving network of the dialed ported number.  
   The other three schemes involve call setup or signaling with the 
   donor network.   
    
   Only the OR scheme requires the setup of two physical call segments, 
   one from the Originating Network to the donor network and the other 
   from the donor network to the new serving network.  The OR scheme is 
   the least efficient in terms of using the network resources.  The 
   QoR and Dropback schemes set up calls to the donor network first but 
   release the call back to the Originating Network that then initiates 
   a new call to the Current Serving Network.  For the QoR and Dropback 
   schemes, circuits are still reserved one by one between the 
   Originating Network and the donor network when the Originating 
   Network sets up the call towards the donor network.  Those circuits 
   are released one by one when the call is released from the donor 
   network back to the Originating Network.  The ACQ scheme is the most 
   efficient in terms of using the switching and transmission 
   facilities for the call. 
    
   Both the ACQ and QoR schemes involve Centralized NPDBs for the 
   Originating Network to retrieve the routing information.  
   Centralized NPDB means that the NPDB contains ported number 
   information from multiple networks.  This is in contrast to the 
   internal network-specific NPDB that is used for the Dropback and OR 
   schemes.  The internal NPDB only contains information about the 
   numbers that were ported out of the donor network.  The internal 
   NPDB can be a stand-alone database that contains information about 
   all or some ported-out numbers from the donor network.  It can also 
   reside on the donor switch and only contains information about those 
   numbers ported out of the donor switch.  In that case, no query to a 
   stand-alone internal NPDB is required.  The donor switch for a 
   particular phone number is the switch to which the number range is 
   assigned from which that phone number was originally assigned. 
    
   For example, number ranges in the North American Numbering Plan 
   (NANP) are usually assigned in the form of central office codes (CO 
   codes) comprising a six-digit prefix formatted as a NPA+NXX.  Thus a 
   switch serving +1 202-533 would typically serve +1 202-533-2000 thru 
   +1 202-533-9999. In major cities, switches usually host several CO 
   codes.  NPA stands for Numbering Plan Area that is also known as the 
   area code.  It is three-digit long and has the format of NXX where N 
   is any digit from 2 to 9 and X is any digit from 0 to 9.  NXX in the 
   NPA+NXX format is known as the office code that has the same format 
   as the NPA.  When the first number out of an NPA+NXX code is ported 
   out to another switch, that NPA+NXX is called portable NPA+NXX. 
    
   Similarly, in other national E.164 plans, number ranges cover a 
   contiguous range of numbers within that range.  Once a number within 
   that range has ported away from the donor network, all numbers in 
   that range are considered potentially ported and should be queried 
   in the NPDB. 
  
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   The ACQ scheme has two versions.  One version is for the Originating 
   Network to always query the NPDB when a call is received from the 
   caller regardless whether the dialed directory number is ported or 
   not. The other version is to check whether the dialed directory 
   number belongs to any portable number range.  If yes, an NPDB query 
   is sent. If not, no NPDB query is sent.  The former performs better 
   when there are many portable number ranges.  The latter performs 
   better when there are not too many portable number ranges at the 
   expense of checking every call to see whether NPDB query is needed.  
   The latter ACQ scheme is similar to the QoR scheme except that the 
   QoR scheme uses call setup and relies on the donor network to 
   indicate "number ported out" before launching the NPDB query. 
    
    
6. Database Queries in the NP Environment 
    
   As indicated earlier, the ACQ and QoR schemes require that a switch 
   query the NPDB for routing information.  Various standards have been 
   defined for the switch-to-NPDB interface.  Those interfaces with 
   their protocol stacks are described below.  The term "NPDB" is used 
   for a stand-alone database that may support just one or some or all 
   of the interfaces mentioned below.  The NPDB query contains the 
   dialed directory number and the NPDB response contains the routing 
   number.  There are certainly other information that is sent in the 
   query and response.  The primary concern is to get the routing 
   number from the NPDB to the switch for call routing. 
    
    
6.1 U.S. and Canada 
    
   One of the following five NPDB interfaces can be used to query an 
   NPDB: 
    
   (a) Advanced Intelligent Network (AIN) using the ANSI version of the 
       Intelligent Network Application Part (INAP) [ANSI SS] [ANSI DB].  
       The INAP is carried on top of the protocol stack that includes 
       the American National Standards Institute (ANSI) Message 
       Transfer Part (MTP) Levels 1 through 3, ANSI Signaling 
       Connection Control Part (SCCP), and ANSI Transaction 
       Capabilities Application Part (TCAP).  This interface can be 
       used by the wireline or wireless switches, is specific to the 
       LRN implementation of LNP in North America, and is modeled on 
       the PODP trigger defined in the AIN 0.1 call model.  
    
   (b) Intelligent Network (IN), which is similar to the one used for 
       querying the 800 databases.  The IN protocol is carried on top 
       of the protocol stack that includes the ANSI MTP Levels 1 
       through 3, ANSI SCCP, and ANSI TCAP.  This interface can be used 
       by the wireline or wireless switches. 
    
   (c) ANSI IS-41 [IS41] [ISNP], which is carried on top of the 
       protocol stack that includes the ANSI MTP Levels 1 through 3, 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
       ANSI SCCP, and ANSI TCAP.  This interface can be used by the IS-
       41 based cellular/Personal Communication Services (PCS) wireless 
       switches (e.g., AMPS, TDMA and CDMA).  Cellular systems use 
       spectrum at 800 MHz range and PCS systems use spectrum at 1900 
       MHz range. 
    
   (d) Global System for Mobile Communication Mobile Application Part 
       (GSM MAP) [GSM], which is carried on top of the protocol stack 
       that includes the ANSI MTP Levels 1 through 3, ANSI SCCP, and 
       International Telecommunication Union - Telecommunication Sector  
       (ITU-TS) TCAP.  It can be used by the PCS1900 wireless switches 
       that are based on the GSM technologies.  GSM is a series of 
       wireless standards defined by the European Telecommunications 
       Standards Institute (ETSI). 
    
   (e) ISUP triggerless translation.  NP translations are performed 
       transparently to the switch network by the signaling network 
       (e.g. STPs or signaling gateways).  ISUP IAM messages are 
       examined to determine if the CdPN field has already been 
       translated, and if not, an NPDB query is performed, and the 
       appropriate parameters in the IAM message modified to reflect 
       the results of the translation.   The modified IAM message is 
       forwarded by the signaling node on to the designated DPC in a 
       transparent manner to continue call setup. 
    
    
   Wireline switches have the choice of using either (a), (b), or (e).  
   IS-41 based wireless switches have the choice of using (a), (b), 
   (c), or (e).  PCS1900 wireless switches have the choice of using 
   (a), (b), (d), or (e). In the North America, service provider 
   portability will be supported by both the wireline and wireless 
   systems, not only within the wireline or wireless domain but also 
   across the wireline/wireless boundary.  However, this is not true in 
   Europe where service provider portability is usually supported only 
   within the wireline or wireless domain, not across the 
   wireline/wireless boundary due to explicit use of service-specific 
   number range prefixes.  The reason is to avoid caller confusion 
   about the call charge. GSM systems in Europe are assigned 
   distinctive destination network codes, and the caller pays a higher 
   charge when calling a GSM directory number. 
    
      
6.2 Europe 
    
   One of the following three interfaces can be used to query an NPDB: 
    
   (a) Capability Set 1 (CS1) of the ITU-TS INAP [CS1], which is 
       carried on top of the protocol stack that includes the ITU-TS 
       MTP Levels 1 through 3, ITU-TS SCCP, and ITU-TS TCAP. 
    
   (b) Capability Set 2 (CS2) of the ITU-TS INAP [CS2], which is 
       carried on top of the protocol stack that includes the ITU-TS 

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
       MTP Levels 1 through ITU-TS MTP Levels 1 through 3, ITU-TS SCCP, 
       and ITU-TS TCAP. 
    
   (c) ISUP triggerless translation.  NP translations are performed 
       transparently to the switch network by the signaling network 
       (e.g. STPs or signaling gateways).  ISUP IAM messages are 
       examined to determine if the CdPN field has already been 
       translated, and if not, an NPDB query is performed, and the 
       appropriate parameters in the IAM message modified to reflect 
       the results of the translation.   The modified IAM message is 
       forwarded by the signaling node on to the designated DPC in a 
       transparent manner to continue call setup. 
    
    
   Wireline switches have the choice of using either (a), (b), or (c); 
   however, all the implementations in Europe so far are based on CS1.  
   As indicated earlier that number portability in Europe does not go 
   across the wireline/wireless boundary.  The wireless switches can 
   also use (a) or (b) to query the NPDBs if those NPDBs contains 
   ported wireless directory numbers.  The term "Mobile Number 
   Portability (MNP)" is used for the support of service provider 
   portability by the GSM networks in Europe.  
    
   In most, if not all, cases in Europe, the calls to the wireless 
   directory numbers are routed to the wireless donor network first.  
   Over there, an internal NPDB is queried to determine whether the 
   dialed wireless directory number has been ported out or not.  In 
   this case, the interface to the internal NPDB is not subject to 
   standardization. 

   MNP in Europe can also be supported via MNP Signaling Relay Function 
   (MNF-SRF).  Again, an internal NPDB or a database integrated at the 
   MNP-SRF is used to modify the SCCP Called Party Address parameter in 
   the GSM MAP messages so that they can be re-directed to the wireless 
   donor network.   Call routing involving MNP will be explained in 
   Section 7.2. 
    
    
7. Call Routing in the NP Environment 
 
   This section discusses the call routing after the routing 
   information has been retrieved either through an NPDB query or an 
   internal database lookup at the donor switch, or from the Integrated 
   Services Digital Network User Part (ISUP) signaling message (e.g., 
   for the Dropback scheme).  For the ACQ, QoR and Dropback schemes, it 
   is the Originating Network that has the routing information and is 
   ready to route the call.  For the OR scheme, it is the donor network 
   that has the routing information and is ready to route the call.   
    
   A number of triggering schemes may be employed that determine where 
   in the call path the NPDP query is performed.  In the US an ˘N-1÷ 
   policy is used, which essentially says that for local calls, the 
   orinigating local carriers performs the query, otherwise, the long 
  
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   distance carrier is expected to.  To ensure independence of the 
   actual trigger poligy employed in any one carrier, forward call 
   signaling is used to flag that an NPDB query has already been 
   performed and to therefore suppress any subsequent NP triggers that 
   may be encountered in downstream switches, in downstream networks.  
   This allows the earliest able network in the call path to perform 
   the query without introducing additional costs and call setup delays 
   were redundant queries performed downstream. 
     
7.1 U.S. and Canada 
    
   In the U.S. and Canada, a ten-digit North American Numbering Plan 
   (NANP) number called Location Routing Number (LRN) is assigned by to 
   every switch involved in NP.  In the NANP, a switch is not reachable 
   unless it has a unique number range (CO code) assigned to it.  
   Consequently, the LRN for a switch is always assigned out of a CO 
   code that is assigned to that switch. 
    
   The LRN assigned to a switch currently serving a particular ported 
   telephone number is returned as the network routing address in the 
   NPDB response.  The service portability scheme that was adopted in 
   the North America is very often referred to as the LRN scheme or 
   method. 
    
   LRN serves as a network address for terminating calls served off 
   that switch using ported numbers.  The LRN is assigned by the switch 
   operator using any of the unique CO codes (NPA+NXX) assigned to that 
   switch.  The LRN is consider a non-dialable address, as the same 10-
   digit number value may be assigned to a line on that switch.  A 
   switch may have more than one LRN. 
    
   During call routing/processing, a switch performs an NPDB query to 
   obtain the LRN associated with the dial directory number.  When 
   formulating the ISUP Initial Address Message (IAM) to be sent to the 
   next switch, the switch puts the ten-digit LRN in the ISUP Called 
   Party Number (CdPN) parameter and the originally dialed directory in 
   the ISUP Generic Address parameter (GAP).  A new code in the GAP was 
   defined to indicate that the address information in the GAP is the 
   dialed directory number.  NPDB queries are performed for all the 
   dialed directory numbers whose NPA+NXX codes are marked as portable 
   NPA+NXX at that switch.  A new bit in the ISUP Forward Call 
   Indicator (FCI) parameter, the Translated Called Number Indicator 
   (TCNI) bit, is set to imply that NPDB query has already been 
   performed.  All the switches in the downstream will not perform the 
   NPDB query if the TCNI bit is set. 
    
   When the terminating switch receives the IAM and sees the TCNI bit 
   in the FCI parameter set and its own LRN in the CdPN parameter, it 
   retrieves the originally dialed directory number from the GAP and 
   uses the dialed directory number to terminate the call. 
    
   A dialed directory with a portable NPA+NXX does not imply that 
   directory number has been ported.  The NPDBs currently do not store 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   records for non-ported directory numbers.  In that case, the NPDB 
   will return the same dialed directory number instead of the LRN.  
   The switch will then set the TCNI bit but keep the dialed directory 
   number in the CdPN parameter. 
    
   In the real world environment, the Originating Network is not always 
   the one that performs the NPDB query.  For example, it is usually 
   the long distance carriers that query the NPDBs for long distance 
   calls.  In that case, the Originating Network operated by the local 
   exchange carrier (LEC) simply routes the call to the long distance 
   carrier that is to handle that call.   A wireless network acting as 
   the Originating Network can also route the call to the 
   interconnected local exchange carrier network if it does not want to 
   support the NPDB interface at its mobile switches. 
    
    
7.2 Europe 
    
   In Europe, a routing number is prefixed to the dialed directory 
   number.  The ISUP CdPN parameter in the IAM will contain the routing 
   prefix and the dialed directory number.  For example, United Kingdom 
   uses routing prefixes with the format of 5XXXXX and Italy uses 
   CXXXXXXXX as the routing prefix.  The networks use the information 
   in the ISUP CdPN parameter to route the call to the New/Current 
   Serving Network. 
    
   The routing prefix can identify the Current Serving Network or the 
   Current Serving Switch of a ported number.  For the former case, 
   another query to the "internal" NPDB at the Current Serving Network 
   is required to identify the Current Serving Switch before routing 
   the call to that switch.  This shields the Current Serving Switch 
   information for a ported number from the other networks at the 
   expense of an additional NPDB query.  Another routing number, may be 
   meaningful within the Current Serving Network, will replace the 
   previously prefixed routing number in the ISUP CdPN parameter.  For 
   the latter case, the call is routed to the Current Serving Switch 
   without an additional NPDB query. 
    
   When the terminating switch receives the IAM and sees its own 
   routing prefix in the CdPN parameter, it retrieves the originally 
   dialed directory number after the routing prefix, and uses the 
   dialed directory number to terminate the call.  
    
   In addition to the addition of the routing prefix to the CdPN 
   parameter, some other information may be added/modified as is listed 
   in the draft ITU-T Recommendation Q.769.1 [ISUP].   Those 
   enhancements in the ISUP to support number portability are briefly 
   described below.   
    
   Three methods can be used to transport the Directory Number (DN) and 
   the Routing Number (RN): 
    

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   (a) Two separate parameters with the CdPN parameter containing the 
      RN and a new Called Directory Number (CdDN) parameter containing 
      the DN.  A new Nature of Address (NOA) indicator in the CdPN 
      parameter is defined to indicate that the RN is in the CdPN 
      parameter.  The switches use the CdPN parameter to route the call 
      as is done today. 
    
   (b) Two separate parameters with the CdPN parameter containing the 
      DN and a new Network Routing Number (NRN) parameter containing 
      the RN.  This method requires that the switches use the NRN 
      parameter to route the call. 
    
   (c) Concatenated parameter with the CdPN parameter containing the RN 
      plus the DN.  A new Nature of Address (NOA) indicator in the CdPN 
      parameter is defined to indicate that the RN is concatenated with 
      the DN in the CdPN parameter.  
    
   There is also a network option to add a new ISUP parameter called 
   Number Portability Forwarding Information parameter.  This parameter 
   has a four-bit Number Portability Status Indicator field that can 
   provide an indication whether number portability query is done for 
   the called directory number and whether the called directory number 
   is ported or not if the number portability query is done. 
    
   Please note that all those enhancements are for national use.  This 
   is because number portability is supported within a nation.  Within 
   each nation, the telecommunications industry or the regulatory 
   bodies can decide which method or methods to use.  Number 
   portability related parameters and coding are never passed across 
   the national boundaries. 
    
   As indicated earlier, an originating wireless network can query the 
   NPDB and concatenate the RN with DN in the CdPN parameter and route 
   the call directly to the Current Serving Network.   
    
   If NPDBs do not contain information about the wireless directory 
   numbers, the call, originated from either a wireline or a wireless 
   network, will be routed to the Wireless donor network.  Over there, 
   an internal NPDB is queried to retrieve the RN that then is 
   concatenated with the DN in the CdPN parameter. 
    
   If MNP-SRF is supported, the Gateway Mobile Services Switching 
   Center (GMSC) at the wireless donor network, when receiving a call 
   from the wireline network or originated from within its network, can 
   send the GSM MAP Send Routing Information (SRI) message to the MNP-
   SRF.  The MNP-SRF interrogates an internal or integrated NPDB for 
   the RN of the MNP-SRF of the wireless Current Serving Network and 
   prefixes the RN to the dialed wireless directory number in the 
   global title address information in the SCCP Called Party Address 
   (CdPA) parameter.  This SRI message will be routed to the MNP-SRF of 
   the wireless Current Serving Network, which then responds with an 
   acknowledgement by providing the RN plus the dialed wireless 
   directory number as the Mobile Station Roaming Number (MSRN).  The 
  
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   GMSC of the Wireless donor network formulates the ISUP IAM with the 
   RN plus the dialed wireless directory number in the CdPN parameter 
   and routes the call to the Wireless Current Serving Network.  A GMSC 
   of the Wireless Current Serving Network receives the call and sends 
   an SRI message to the associated MNP-SRF where the global title 
   address information of the SCCP CdPA parameter contains only the 
   dialed wireless directory number.  The MNP-SRF then replaces the 
   global title address information in the SCCP CdPA parameter with the 
   address information associated with a Home Location Register (HLR) 
   that host the dialed wireless directory number and forwards the 
   message to that HLR after verifying that the dialed wireless 
   directory number is a ported-in number.   The HLR then returns an 
   acknowledgement by providing an MSRN for the GMSC to route the call 
   to the MSC that currently serves the mobile station that is 
   associated with the dialed wireless directory number.  Please see 
   [MNP] for details and additional scenarios. 
    
8. Number Conservation Methods Enabled by NP 
 
   In addition to porting numbers NP provides the ability for number 
   administrators to assign numbering resources to operators in smaller 
   increments.  Today it is common for numbering resources to be 
   assigned to telephone operators in a large block of consecutive 
   telephone numbers (TN).  For example, in North America these blocks 
   contain 10,000 TNs and are of the format NXX+0000 to NXX+9999.  
   Operators are assigned a specific NXX, or block.  That operator is 
   referred to as the block holder.  In that block there are 10,000 TNs 
   with line numbers ranging from 0000 to 9999.   
    
   Instead of assigning an entire block to the operator NP allows the 
   administrator to assign a sub-block or even an individual telephone 
   number.  This is referred to as block pooling and individual 
   telephone number (ITN) pooling, respectively.   
    
8.1 Block Pooling 
    
   Block Pooling refers to the process whereby the number administrator 
   assigns a range of numbers defined by a logical sub-block of the 
   existing block.  Using North America as an example, block pooling 
   would allow the administrator to assign sub-blocks of 1,000 TNs to 
   multiple operators.  That is, NXX+0000 to NXX+0999 can be assigned 
   to operator A, NXX+1000 to NXX+1999 can be assigned to operator B, 
   NXX-2000 to 2999 can be assigned to operator C, etc.  In this 
   example block pooling divides one block of 10,000 TNs into ten 
   blocks of 1,000 TNs.   
    
   Porting the sub-blocks from the block holder enables block pooling.  
   Using the example above operator A is the block holder, as well as, 
   the holder of the first sub-block, NXX+0000 to NXX+0999.  The second 
   sub-block, NXX+1000 to NXX+1999, is ported from operator A to 
   operator B.  The second sub-block, NXX+2000 to NXX+2999, is ported 
   from operator A to operator C, and so on.  NP administrative 

  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   processes and call processing will enable proper and efficient 
   routing.   
    
   From a number administration and NP administration perspective block 
   pooling introduces a new concept, that of the sub-block holder.  
   Block pooling requires coordination between the number 
   administrator, the NP administrator, the block holder, and the sub-
   block holder.  Block pooling must be implemented in a manner that 
   allows for NP within the sub-blocks.  Each TN can have a different 
   serving operator, sub-block holder, and block holder.   
    
8.2 ITN Pooling 
    
   ITN pooling refers to the process whereby the number administrator 
   assigns individual telephone numbers to operators.  Using the North 
   American example, one block of 10,000 TNs can be divided into 10,000 
   ITNs.  ITN is more commonly deployed in freephone services.   
    
In ITN the block is not assigned to an operator but to a central 
administrator.  The administrator then assigns ITNs to operators.  NP 
administrative processes and call processing will enable proper and 
efficient routing. 
 
10. Conclusion 
    
   There are three general areas of impact to IP telephony work-in-
   progress at IETF: 
    
   1. NP implementation or emulation in IP telephony 
   2. Interoperation between NP in GSTN and IP telephony 
   3. Interconnection to NP administrative environment 
    
   A good understanding of how number portability is supported in the 
   GSTN is important when addressing the interworking issues between IP 
   based networks and the GSTN.  This is especially important when the 
   IP based network needs to route the calls to the GSTN.  As shown in 
   Section 6, there are a variety of standards with various protocol 
   stacks for the switch-to-NPDB interface.  If an entity in the 
   Internet needs to query those existing NPDBs for routing number 
   information to terminate the calls to the destination GSTN, it would 
   be impractical, if not an impossible, job for that entity to support 
   all those interface standards. 
    
   If not all of the IP telephony gateways (GWs) can reach the Current 
   Serving Switch of a ported number, then the IP based network may 
   need to obtain the RN of the Current Serving Network or Switch 
   before selecting the terminating GW to terminate a call to the GSTN.  
   The RN should be passed to the terminating GW so that another NPDB 
   query at the terminating GW or the terminating GSTN is avoided.  As 
   indicated earlier, the ISUP support of the number portability is 
   confined within the national boundary (e.g., the RN contains a 
   national number instead of an international number).  When routing a 
   call to the terminating GSTN from the IP based network, the 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   signaling messages, be it ISUP, Session Initiation Protocol (SIP), 
   or others, will need to be enhanced to carry the number portability 
   related information so that the terminating GW or GSTN can make use 
   of the information without an additional NPDB lookup.   
    
   Overlap signaling exists in the GSTN.  For a call routing from the 
   originating GSTN to the terminating GSTN via the IP based network 
   that involves overlap signaling, NP will impact the call processing 
   within the IP based network if they must deal with the overlap 
   signaling.  The entities in the IP based networks that are to 
   retrieve the NP information (e.g., the routing number) must collect 
   a complete called party number information before retrieving the NP 
   information for a ported number.  Otherwise, the information 
   retrieval won't be successful. 
    
   The IP based networks also may need to support some forms of number 
   portability in the future if E.164 numbers [E164] are assigned to 
   the IP based end users.  Many different types of networks use E.164 
   numbers to identify the end users or terminals in those networks.  
   Number portability among those various types of networks may also 
   need to be supported in the future. 
 
    
11. References 
    
    
    
   [ANSI OSS] ANSI Technical Requirements No. 1, "Number Portability -
        Operator Services Switching Systems," April 1999. 
    
   [ANSI SS] ANSI Technical Requirements No. 2, "Number Portability -
        Switching Systems," April 1999. 
             
   [ANSI DB] ANSI Technical Requirements No. 3, "Number Portability 
        Database and Global Title Translation," April 1999.         
          
   [CS1] ITU-T  Q-series  Recommendations - Supplement 4, "Number 
        portability Capability set 1 requirements for service provider 
        portability (All call query and onward routing)," May 1998. 
    
   [CS2] ITU-T  Q-series  Recommendations - Supplement 5, "Number 
        portability -Capability set 2 requirements for service provider 
        portability (Query on release and Dropback)," March 1999. 
    
   [E164] ITU-T Recommendation E.164, "The International Public 
        Telecommunications Numbering Plan," 1997. 
    
   [FRS] NANC, "Functional Requirements Specification - NPAC SMS, 
        Version 2.0.2," September 1, 1999. 
    
   [GSM]  GSM 09.02: "Digital cellular telecommunications system (Phase 
        2+); Mobile Application Part (MAP) specification". 
    
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
    
   [ICC] ICC, "Generic Switching & Signaling Requirements for Number 
        Portability, Issue 1.05," August 1, 1997. 
    
   [IIS] NeuStar (formerly Lockheed Martin IMS Corporation), prepared 
        for the North American Numbering Council (NANC),"NPAC SMS 
        interoperable Interface Specification, Version 2.0.2," 
        September 1, 1999. 
    
   [IS41] TIA/EIA IS-756 Rev. A, "TIA/EIA-41-D Enhancements for 
        Wireless Number Portability Phase II (December 1998)"Number 
        Portability Network Support," April 1998. 
    
   [ISUP] ITU-T COM 11-R 162-E, Draft Recommendation Q.769.1, 
        "Signaling System No. 7 - ISDN User Part Enhancements for the 
        Support of Number Portability," May 1999. 
    
   [MNP] Draft GSM 03.66 V7.2.0 (1999-11) European Standard 
        (Telecommunications series) Digital cellular telecommunications 
        system (Phase 2+); Support of Mobile Number Portability (MNP); 
        Technical Realisation; Stage 2; (GSM 03.66 Version 7.2.0 
        Release 1998). 
    
   [RFC] Scott Bradner, RFC2026, "The Internet Standards Process -- 
        Revision 3," October 1996. 
    
    
12. Acknowledgments 
    
   The authors would like to thank Monika Muench for providing 
   reference information on ISUP and MNP. 
    
    
13. Author's Addresses 
    
   Mark D. Foster 
   NeuStar, Inc. 
   1120 Vermont Avenue, NW, 
   Suite 550 
   Washington, D.C. 20005 
   United States 
    
   Phone: +1-202-533-2800 
   Fax:   +1-202-533-2975 
   Email: mark.foster@neustar.com 
          
    
   Tom McGarry 
   NeuStar, Inc. 
   1120 Vermont Avenue, NW, 
   Suite 550 
   Washington, D.C. 20005 
   United States 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
    
   Phone: +1-202-533-2810 
   Fax:   +1-202-533-2975 
    
    
   James Yu 
   NeuStar, Inc. 
   1120 Vermont Avenue, NW,  
   Suite 550 
   Washington, D.C. 20005 
   United States 
    
   Phone: +1-202-533-2814 
   Fax:   +1-202-533-2975 
   Email: james.yu@neustar.com 
    
    
    



































  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
APPENDICES  
 
APPENDIX A. NP Requirements in the North America 
 
A.1 Background 
 
   The North American telecommunications industry began to seriously 
   investigate methods of providing local number portability (LNP) in 
   late 1994.  On July 13, 1995, the Federal Communications Commission 
   (FCC) in the U.S. issued a Notice of Proposed Rulemaking (NPRM) FCC 
   Docket Number 95-116 that opened discussion on NP and sought 
   comments on a wide variety of policy and technical issues related to 
   NP. 
    
   In 1995 and 1996 several state regulatory bodies, notably the 
   Illinois Commerce Commission (ICC), began the process of officially 
   selecting the architecture to be used for NP in their respective 
   states.  After considerable discussion and deliberation, the 
   "Location Routing Number (LRN)" scheme was selected by Illinois, and 
   other states.  The switching and signaling requirements for number 
   portability developed in the Illinois LNP workshop under the 
   auspices of the ICC became the basis of the de facto North American 
   industry standards [ICC].  The activities on number portability in 
   the North America also interacted with activities in many other 
   parts of world. 
 
A.2 Performance/Legal/Regulatory Requirements 
    
   After substantial industry discussion and debate, and extensive 
   comments filed with the FCC, the FCC and the US telecommunications 
   industry set the following minimum performance criteria for LNP: 
    
   1. Support existing network services, features and capabilities. 
   2. Efficiently use numbering resources. 
   3. Not require end users to change their telecommunication numbers.  
   4. Not require telecommunications carrier to rely on databases, 
     other network facilities, or services provided by other 
     telecommunications carriers in order to route calls to proper 
     termination point. 
   5. Not result in unreasonable degradation in service quality or 
     network reliability when implemented. 
   6. Not result in unreasonable degradation of service quality or 
     network reliability when customers switch carriers. 
   7. Not result in a carrier having a proprietary interest. 
   8. Be able to accommodate location and service portability in the 
     future. 
   9. Have no significant adverse impact outside areas where number 
     portability is deployed. 
    
   In July 1996, the FCC issued the First Report and Order on LNP under 
   95-116, calling for the deployment of LNP across the US starting in 
   1997.  The FCC did not mandate any specific implementation of LNP in 
   the US, but it did call upon the industry to develop and endorse a 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
   national standard that would ensure interoperability with all 
   industry segments, including wireless.  While providing overall 
   guidelines and requirements for LNP, it did explicitly state that 
   the LRN method met these requirements, whereas alternate proposals 
   (such as QoR) did not. 
    
   A core requirement was that a carrier who is serving ported numbers 
   need not be reliant on any other carrier (especially the donor 
   network) for completing calls, whether for call transport/routing or 
   for signaling.  That's not to say that a carrier couldn't 
   voluntarily opt to use another carrier or the donor network for 
   queries or call routing.  But the key is voluntarily.  This 
   requirement was imposed on all NP implementations in the U.S. for 
   common carrier telephony services regardless of the network 
   technology employed. 
    
   Similar requirements were adopted by the Canadian Radio and 
   Television Commission (CRTC), the equivalent of the FCC in Canada, 
   and in a number of regulatory and industry bodies in other countries 
   (e.g., Belgium, Denmark, Spain, Switzerland) which resulted in the 
   use of centralized NPDBs to support number portability. 
    
   In the U.S. and Canada, the ACQ scheme was adopted because it does 
   not rely on the donor network for call routing (see requirements 
   numbers 4 and 7) and it can accommodate location and service 
   portability in the future.  
     
   In the U.S. and Canada, there is also the "N-1" guideline that 
   recommends that the network next to the destination network perform 
   the NPDB query if the NPDB query has not been done or the routing 
   information is not available (e.g., due to signaling interworking).  
   This is to prevent the call from being re-routed at the donor 
   network.  In the U.S., the wireline carriers are required to support 
   NP in certain service areas in phases.  The wireless carriers' 
   support of NP has been postponed until November 2002. 
    
    
















  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
APPENDIX B. NP Administration Process in the North America 
 
B.1 Business Model 
    
   Figure B.1 shows the NP business model that was adopted in the U.S. 
   and Canada.  The U.S. is divided into seven regions coinciding with 
   the boundaries of the original seven Regional Bell Operating Company 
   (RBOC) regions.  This was done to facilitate the formation of 
   separate contracting and administrative areas (formed as limited 
   liability companies) for LNP in the US intentionally coinciding with 
   the original RBOC boundaries, thus enabling each RBOC to participate 
   singly in each of these areas. 
    
   NeuStar, Inc., formerly the Communication Industry Services business 
   unit with Lockheed Martin IMS, was selected in open competitive 
   procurements conducted by the industry to be the Number Portability 
   Administration Center (NPAC) provider for all the seven NPAC regions 
   (Midwest, Northeast, Mid-Atlantic, Southwest, Southeast, Western, 
   and West Coast) in the U.S. Lockheed Martin was subsequently named 
   as the NPAC provider in Canada as well.  Each Limited Liability 
   Corp. (LLC) in the seven U.S. regions and Canadian Consortium 
   maintain largely identical contracts with with NeuStar covering each 
   region. 
    
   The FCC and North American Numbering Council (NANC) oversee the 
   technical and operational standards, originally developed by 
   Lockheed Martin and offered as open industry standards, and cost 
   recovery rulemakings. 
    
   Each LLC signed a master contract with NeuStar that set the prices 
   and terms and provided the form of User Agreement for NeuStar to 
   sign with each individual NPAC user.  NPAC users are any bona fide 
   entity which either ports numbers or subscribes to updates to the 
   NPDB provided by the NPAC. 
    
    
         +--------+             +----------+ 
         |  FCC   |------------>|   State  | 
         |  NANC  |<---+   +--->|   PUCs   | 
         +--------+    |   |    +----------+ 
                       |   | 
                       v   v      (Master 
                +--------------+  Agreement) +----------+ 
                | Regional LLC |<----------->|   NPAC   | 
                |   Contract   |             | (NeuStar)| 
                | Administrator|             +----------+ 
                +--------------+                  ^ 
                         ^                        | 
                         |                        | 
                         v                        | 
                   +----------+                   | 
                   |   NPAC   |<------------------+ 
                   |   Users  |  (One User Agreement per User) 
  
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             Number Portability in the GSTN: An Overview     March 2000 
 
 
                   +----------+ 
    
              Figure B.1 - NP Administration Business Model in US. 
    
    
B.2 NPAC Architecture 
    
   Figure B.2 shows the architecture for number portability 
   administration in the U.S. and Canada.  NeuStar is the NPAC Service 
   Management System (SMS) service provider in the architecture 
   diagram. 
    
     (Carrier Facilities)                    :    (NPAC Facilities) 
                          +---------+        : 
                          |   SOA   |        : 
                          |         |-------------------+ 
                          +---------+        :          | 
                                             :          | 
                                             :     +----------+ 
                                             :     | NPAC/SMS | 
                                             :     | (NeuStar)| 
                                             :     +----------+ 
                                             :          | 
      +---------+         +---------+        :          | 
      |  NPDB   |---------|  LSMS   |-------------------+ 
      |(e.g.SCP)|         |         |        : 
      +---------+         +---------+        : 
                                             : 
    
                     Figure B.2 - NPAC Architecture. 
 
    
   The interface between the Service Order Administration (SOA) and the 
   NPAC/SMS is for provisioning ported end-user data including the 
   support of the creation, cancellation, retrieval and update of 
   subscription, service provider, and network information.  The SOAs 
   are operated by the local exchange carriers. 
    
   The interface between the Local Service Management System (LSMS) and 
   the NPAC/SMS is mainly used for downloading ported number 
   information from the NPAC/SMS to the LSMS.  The LSMS then updates 
   the NPDB.  A local exchange carrier may operate the LSMS if it 
   decides to deploy an NPDB itself.  A service bureau can also operate 
   the LSMS to provision several LECs' NPDBs or operate the LSMS and 
   the NPDB for the operators (e.g., LECs or long distance carriers) to 
   query.  The interface between the LSMS and the NPDB is up to the 
   entities that operate them. 
    
   The functional requirement specification developed under the 
   auspices of the North American Numbering Council (NANC) defines the 
   external functionality of the NPAC SMS [FRS].  The interfaces 
   between the NPAC/SMS and the SOA or LSMS use standards-based 
   communications and security technologies and are made public [IIS].  
  
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   Please note that only the information about the ported numbers is 
   stored at the NPAC databases and the NPDBs at present. 
    
    
B.3 NPAC SMS Functions 
    
   This section provides a list of the NPAC SMS functions.  Please see 
   [FRS] for details. 
    
  - Provisioning Service: For the new service provider to notify the 
     NPAC SMS of a provision request for a ported number and to send an 
     activation notice to activate the update from the NPAC SMS to the 
     LSMS. 
   
  - Disconnect Service: For handling disconnection of the telephony 
     service for a ported number. 
   
  - Repair Service: For resolving problems detected either by a Service 
     Provider or by a customer contacting a Service Provider.  
   
  - Conflict Resolution: For resolving a conflict when there is 
     disagreement between the old and new Service Providers as to who 
     will be providing service for the telephone number (TN).  Please 
     note that the processes for obtaining authorization from the 
     customer to port a number are defined by the Service Providers.  
     The NPAC is not involved in obtaining or verifying customer 
     approval to port a telephone number. 
   
  - Disaster Recovery and Backup: For having a backup facility and the 
     disaster recovery procedures in place for planned and unplanned 
     downtime at the primary facility. 
   
  - Order Cancellation: For the new Service Provider to cancel a 
     previously submitted but not activated provision request. 
    
   - Audit Request: For troubleshooting customer problems and also as a 
     maintenance process to ensure data integrity across the entire NP 
     network. 
    
   - Report Request: For supporting report generation for pre-defined 
     and ad-hoc reports. 
    
   - Data Management: For managing network, Service Provider, and 
     customer subscription data.  The network data defines the 
     configuration of the NP service and network and includes such data 
     as: participating Service Providers, NPA-NXXs that are portable, 
     and LRNs associated with each Service Provider.  The Service 
     Provider data indicates who the NP Service Providers are and 
     includes location, contact name, security, routing, and network 
     interface information.  The subscription data indicates how local 
     number portability should operate to meet subscribers' needs. 
    

  
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   - NPA-NXX Split Processing: For the administration of the 
     information for NPA split (the current NPA, the new NPA, and the 
     affected NXXs) plus the beginning and end date of the permissive 
     dialing period. 
     
   - Business Support: For supporting service providers that have 
     different needs for business hours and days available for porting.  
    
   - Notification Recovery: For allowing a Service Provider to capture, 
     via a recovery process, all notifications that were missed during 
     a downtime period for the Service Provider. 
    









































  
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