Internet Engineering Task Force Martin Taylor Internet Draft CopperCom Document: draft-taylor-megaco-enhalpkgs-00.txt C. Michael Brown Category: Standards Track Nortel Networks April 2001 Megaco/H.248 Enhanced Analog Line Packages Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract This document provides proposed definitions for two supplemental packages for Megaco/H.248. These packages address support of functionality for standard and enhanced telephony services delivered over analog line terminations, including line-side answer supervision and the delivery of call metering pulses. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 [2]. 3. Document Organization The subsequent text in this document is organized into the following major sections: * Introduction * Description of the Extended Analog Line Supervision Package * Description of the Automatic Metering Package * References Taylor & Brown Standards Track _ Expires Oct 2001 1 Megaco/H.248 Enhanced Analog Line Packages April 2001 * Author's addresses 4. Introduction The Analog Line Supervision Package defined in Annex E of RFC3015 [3] supports basic telephony services, using on-hook and off-hook events, and a ringing signal. Some telephony services delivered over analog line terminations have additional supervisory signaling requirements that are not met by this package. The packages defined in this document are intended to meet the needs of the following supervisory signaling functions: Line-side answer supervision _ this function provides a positive notification to a calling line that the called line has answered. This notification may be used by customer premises equipment, for example, to begin timing the call for local billing or charging purposes. Network disconnect _ many switching systems provide this signal following the termination of an active call if a party remains off- hook for some period of time following the other party going on- hook. The network disconnect notification may be used by customer premises equipment to release resources associated with the call. Metering pulses _ metering services provide subscribers with real- time information about charging of calls in progress. These services make use of customer premises equipment that shows a count of "units" consumed by chargeable calls, where each unit has a fixed monetary value. To increment the counter in the metering equipment, the switching system sends certain kinds of pulses over the line, either during the call or immediately following termination of the call. These pulses typically consist of short bursts of 12 kHz or 16 kHz tones, although other types of metering pulse such as brief periods of polarity reversal or 50 Hz tones are also seen. To meet these needs, two supplemental packages are proposed. The Extended Analog Line Supervision package is defined as an extension of the Basic Analog Line Supervision package, and includes two new signals: Line-Side Answer Supervision and Network Disconnect. This package provides support for all the Loop-Start supervisory signaling requirements identified by GR-506 [4]. The Automatic Metering Package provides a means to apply metering pulses on an analog line termination. The package includes signals requesting the automatic application of pulses at fixed intervals as well as the application of pulse bursts, properties that may be used to track the actual number of pulses applied, and an event that may be used to trigger periodic reporting of the count of pulses applied. Taylor & Brown Standards Track _ Expires Oct 2001 2 Megaco/H.248 Enhanced Analog Line Packages April 2001 5. Extended Analog Line Supervision Package PackageID: xal (0x????) Version: 1 Extends: al This package defines events and signals necessary to support analog telephony services where line-side answer supervision and/or network disconnect capabilities are required. 5.1 Properties None. 5.2 Events None. 5.3 Signals Line-side Answer Supervision SignalID: las (0x????) Indicates that the called party has answered. The signal that is sent on the line is provisioned in the MG. Typically this signal involves a reversal of polarity of the current feed on the line. Signal Type: OnOff Additional Parameters: None Network Disconnect SignalID: nd (0x????) Indicates that the far-end party has disconnected. The signal that is sent on the line is provisioned in the MG. Typically this signal involves a brief removal of the dc voltage on the line. Signal Type: Brief Duration: Provisioned Additional Parameters: None 5.4 Statistics None. 5.5 Procedures Taylor & Brown Standards Track _ Expires Oct 2001 3 Megaco/H.248 Enhanced Analog Line Packages April 2001 The Network Disconnect signal is typically used when a called or calling party remains off-hook after the other party has hung up. In these circumstances, some telephony services provide dial tone to the off-hook phone after a period of several seconds has elapsed. The Network Disconnect signal would normally be applied just prior to the re-application of dial tone on the line. 6. Automatic Metering Package PackageID: amet (0x????) Version: 1 Extends: None This package supports the automated application of repetitive metering pulses to an analog line termination. It provides a facility whereby the actual number of metering pulses applied to the termination can be periodically reported to the MGC for verification purposes. 6.1 Properties Current Pulse Count PropertyID: cpc (0x????) Type: Integer Possible values: zero or positive number Defined in: TerminationState Characteristics: Read/Write This property represents the total number of metering pulses that have been applied on an analog line termination since the last time its value was reset to zero by means of the "enable metering" signal defined in this package. Pulse Count Since Last Report PropertyID: pcslr (0x????) Type: Integer Possible values: zero or positive number Defined in: TerminationState Characteristics: Read/Write This property represents the number of metering pulses that have been applied on an analog line termination since the last meter report event, or since the last time its value was reset to zero by means of the "enable metering" signal defined in this package. The recognition of the periodic report event and generation of a corresponding notification resets the value of this property to zero. Taylor & Brown Standards Track _ Expires Oct 2001 4 Megaco/H.248 Enhanced Analog Line Packages April 2001 6.2 Events Periodic report EventID: pr (0x????) This event is used in conjunction with the "enable metering" and "metering pulse burst" signals defined in this package. It is detected when the value of the "pulse count since last report" property reaches the value specified in the "report period" parameter. This event does not have any parameters for the observed event descriptor since it will be reported only when the pulse count since last report reaches the report period, which is a value already known to the MGC. This event is not detected when the application of signals is stopped due to an MG failure, a customer line state event (e.g. on-hook), or by an explicit command from the MGC. The MGC needs to read the value of the property "pulse count since last report" in those cases, using an AuditValue command. EventsDescriptor parameters: Report Period ParameterID: rp (0x????) Type: Integer This parameter specifies the period of metering reports in terms of pulse counts. There is no default value for this parameter, and it must be specified with a non-zero value. ObservedEventsDescriptor parameters: None. 6.3 Signals Enable Metering SignalID: em (0x????) This signal starts the automatic generation of metering pulses on the termination. The type and duration of the pulses to be applied are provisioned in the MG. Signal Type: OnOff Duration: Variable Additional Parameters: Taylor & Brown Standards Track _ Expires Oct 2001 5 Megaco/H.248 Enhanced Analog Line Packages April 2001 Pulse Count ParameterID: pc (0x????) Type: Integer This parameter specifies the number of metering pulses to be applied to the termination. If the value of this parameter is zero, or if no value is supplied for this parameter, then the repetitive application of metering pulses shall continue until stopped by other mechanisms (for example, the detection of an event, or the replacement of the Signals Descriptor). Pulse Repetition Interval ParameterID: pri (0x????) Type: Integer This parameter specifies the interval between repetitions of metering pulses on the line, in milliseconds. It represents the time that should elapse between the leading edge of a pulse and the leading edge of the succeeding pulse. There is no default value for this parameter, and the MGC should always provide a positive non-zero value. Metering Pulse Burst SignalID: mpb (0x????) This signal causes a burst of metering pulses to be applied to the termination. Signal Type: Brief Duration: Variable Additional Parameters: Burst Pulse Count ParameterID: bpc (0x????) Type: Integer This parameter specifies the number of metering pulses to be applied as a burst on the line. The type, duration and pulse repetition interval for the metering pulses comprising the burst are provisioned in the MG. The default value of this parameter, which shall apply if the parameter is omitted from the SignalsDescriptor, is 1. 6.4 Statistics None. Taylor & Brown Standards Track _ Expires Oct 2001 6 Megaco/H.248 Enhanced Analog Line Packages April 2001 6.5 Procedures When the MGC starts automatic metering for a given call, it should initialize the pulse count properties cpc and pcslr by setting their values to zero. On receiving a SignalsDescriptor containing the signal em, an MG shall apply the first metering pulse to the termination immediately, and then apply subsequent metering pulses at intervals as specified by the value of the pulse repetition interval parameter pri. The MG shall increment by one the values of the pulse count properties cpc and pcslr for each metering pulse that is applied to the termination, regardless of whether the pulse was generated as a result of the em signal or as a result of the mpb signal. If the value of the parameter pc associated with the signal em is non-zero, then the repetitive application of metering pulses should be continued until the value of the property cpc is equal to the value of the parameter pc. In this case, the MGC should include a SignalType parameter in the Signals Descriptor, specifying the signal type Brief, to override the OnOff signal type for the signal em. If the value of the parameter pc is zero or if this parameter is not supplied by the MGC, then the repetitive application of metering pulses should continue until either an event (other than pr) is detected, or until the SignalsDescriptor is replaced with a new SignalsDescriptor that does not include the signal em. If, following the application of any metering pulse (regardless of whether it was generated as a result of the signal em or as a result of the signal mbp), the EventsDescriptor contains the event pr, and if the value of pcslr is equal to the value of the EventsDescriptor parameter rp, then the pr event shall be notified, and the value of the property pcslr shall be reset to zero. The detection of the event pr shall not cause the termination of the signal em or the signal mbp, even if the KeepActive flag is not set for the pr event. The repetition rate for the application of metering pulses to the termination may be changed during a call by writing a new SignalsDescriptor containing the signal em, specifying a new value of the pulse repetition interval parameter pri. In this case, the SignalsDescriptor should contain a KeepActive flag for the signal em, and the MG should transition to the new pulse repetition interval after the next metering pulse has been applied. A metering pulse burst may be applied while a metered call is in progress, for example to take account of a chargeable mid-call action by the subscriber. In this case, the MGC should send a new SignalsDescriptor that contains the em signal with a KeepActive flag, together with the mpb signal. The MG should continue to apply Taylor & Brown Standards Track _ Expires Oct 2001 7 Megaco/H.248 Enhanced Analog Line Packages April 2001 metering pulses at the repetition interval specified by the pri parameter of the em signal, while in addition applying the metering pulse burst. The MG should ensure that the pulses comprising the pulse burst are applied in such a manner as not to interfere with the pulses comprising the repetitive background metering, respecting any minimum inter-pulse interval that may be needed to ensure proper recognition of pulses by customer premises equipment. The detection of an event such as on-hook while a metering pulse is being applied to a termination should not cause truncation of the pulse. Once a pulse has started to be applied, the application of the pulse should continue for the full duration provisioned in the MG. 8. Formal Syntax Not applicable. 9. Security Considerations Not applicable. 10. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 3 Cuervo, et al., "Megaco Protocol Version 1.0", RFC 3015, November 2000 4 Telcordia, "Local Switching System Generic Requirements _ Signaling for Analog Interfaces", GR-506-CORE, June 1996 11. Acknowledgments None. 12. Author's Addresses Martin Taylor CopperCom 3651 FAU Boulevard, Suite 300 Boca Raton, FL 33431 Phone: (561) 239 6694 Taylor & Brown Standards Track _ Expires Oct 2001 8 Megaco/H.248 Enhanced Analog Line Packages April 2001 Email: mtaylor@coppercom.com C. Michael Brown Nortel Networks 4008 Chapel Hill Road Research Triangle Park, NC USA 27709 Phone: (919) 991-7767 Email: C.Michael.Brown@nortelnetworks.com Taylor & Brown Standards Track _ Expires Oct 2001 9 Megaco/H.248 Enhanced Analog Line Packages April 2001 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Taylor & Brown Standards Track _ Expires Oct 2001 10