Network Working Group A. Ligot Internet-Draft T. Froment Intended status: Informational Alcatel-Lucent Expires: May 12, 2008 November 9, 2007 Providing guidance for Session Initiation Protocol (SIP) services draft-ligot-bliss-sip-services-guide-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. This Internet-Draft will expire on May 12, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Ligot & Froment Expires May 12, 2008 [Page 1] Internet-Draft SIP Services Guide November 2007 Abstract Implementing Session Initiation Protocol (SIP) advanced features and services requires to use numerous specifications. Today, for each service in the scope of BLISS, one can already find references to many possible specifications which do not cover the same things. Some of them are primitive operations (GRUU, REFER, target dialog, ...), some are requirements or call flow examples, some others have a larger scope: TISPAN specs, SPIT to implement Call Barring... The goal of this document is not to present the best solutions; but to give an overview of every standard specification related to these services, centralizing and categorizing them as input to the working group. Table of Contents 1. Introduction, scope . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Call Forwarding . . . . . . . . . . . . . . . . . . . . . . . 7 3.1. Description . . . . . . . . . . . . . . . . . . . . . . . 7 3.2. Frameworks and requirements . . . . . . . . . . . . . . . 7 3.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 7 3.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 7 4. Call Transfer . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Description . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. Frameworks and requirements . . . . . . . . . . . . . . . 9 4.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 9 4.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 9 5. Hold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1. Description . . . . . . . . . . . . . . . . . . . . . . . 11 5.2. Frameworks and requirements . . . . . . . . . . . . . . . 11 5.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 11 5.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 11 6. Call Baring . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1. Description . . . . . . . . . . . . . . . . . . . . . . . 12 6.2. Frameworks and requirements . . . . . . . . . . . . . . . 12 6.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 12 6.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 12 7. Conference . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1. Description . . . . . . . . . . . . . . . . . . . . . . . 14 7.2. Frameworks and requirements . . . . . . . . . . . . . . . 14 7.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 14 7.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 14 8. Call parking . . . . . . . . . . . . . . . . . . . . . . . . . 16 8.1. Description . . . . . . . . . . . . . . . . . . . . . . . 16 8.2. Frameworks and requirements . . . . . . . . . . . . . . . 16 8.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 16 Ligot & Froment Expires May 12, 2008 [Page 2] Internet-Draft SIP Services Guide November 2007 8.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 16 9. Do not disturb . . . . . . . . . . . . . . . . . . . . . . . . 17 9.1. Description . . . . . . . . . . . . . . . . . . . . . . . 17 9.2. Frameworks and requirements . . . . . . . . . . . . . . . 17 9.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 17 9.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 17 10. Call Completion . . . . . . . . . . . . . . . . . . . . . . . 18 10.1. Description . . . . . . . . . . . . . . . . . . . . . . . 18 10.2. Frameworks and requirements . . . . . . . . . . . . . . . 18 10.3. Call flows samples . . . . . . . . . . . . . . . . . . . . 18 10.4. Specifications . . . . . . . . . . . . . . . . . . . . . . 18 11. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 19 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 13. Security Considerations . . . . . . . . . . . . . . . . . . . 21 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 15.1. Normative References . . . . . . . . . . . . . . . . . . . 23 15.2. Informative References . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29 Intellectual Property and Copyright Statements . . . . . . . . . . 30 Ligot & Froment Expires May 12, 2008 [Page 3] Internet-Draft SIP Services Guide November 2007 1. Introduction, scope BLISS working group is chartered to facilitate effective feature interoperability for advanced services sharing common functional primitives utilizing SIP. In particular, it focuses on advanced call features requiring non-trivial call control. Goal of this document is not to give recommendation or to give a technical appreciation of referenced specifications. So, references that could be found in this document SHOULD NOT be considered as the recommended way of implementing any service. This document aims at providing the current "snapshot" of "SIP services" specifications, centralizing what currently exist. This first version presented here shows that the number of specifications around call features is quite impressive, sometimes individual drafts have addressed a very specific problem that has been forgotten in the internet draft morgue. Some other specifications like TISPAN ones have to be considered from a different point of view: they are most of the time referencing existing IETF specifications when they exist, generally trying to additionally standardize the format of a user profile which contains the configuration elements of the service. This approach assumes that there is a user profile database, operated somewhere, which is of course completely out of IETF concerns. In that case, goal is indeed not to give any appreciation on these external specifications, but it is still useful to describe what does exist, what difference MAY exist between them, and if they diverge, try to explain why. Thus, this document categorizes them in order to outline what is currently missing, which documents can be compared at the same "level", and when overlap between different specifications are identified, start analysing if there is a fundamental protocol change or requirement behind it. Today, service categories that are considered as in-scope of BLISS are the following: o Call forwarding o Call Transfer o Hold o Call Baring o Conference o Call parking o Do not disturb Ligot & Froment Expires May 12, 2008 [Page 4] Internet-Draft SIP Services Guide November 2007 o Call completion This list will be the starting point of this guide, it MAY be extended to other topics in the future if it is considered as useful. For each of these services, it provides: - first, a short description of the service, - second, user's requirements or frameworks which give grounds of any implementation, - third, references to documents that contain call flows showing the application of the service, - finally, a short description of any specification that has been identified (possibly erroneously) as useful to implement a service, giving some "hints" on why it is referenced in this context. Ligot & Froment Expires May 12, 2008 [Page 5] Internet-Draft SIP Services Guide November 2007 2. Terminology 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 RFC 2119 [RFC2119]. Ligot & Froment Expires May 12, 2008 [Page 6] Internet-Draft SIP Services Guide November 2007 3. Call Forwarding 3.1. Description Call forwarding allows users to divert a call from its destination without answering it. There is a few cases of call forwarding. For example, users should be able to forward calls towards another person when he is already on the phone, when he does not answer or when he is unavailable. Call forwarding should also allow users to setup unconditional forwarding based on a set of rules. Call forwarding is also called "Call diversion". 3.2. Frameworks and requirements none found 3.3. Call flows samples o sections 7,8,9 of [I-D.ietf-sipping-service-examples] present some cases of call forwarding. Theses call flows are mainly implementation dependant. TS183 004 [TS183004], from TISPAN, uses call flows like those from sipping-service-examples but gives more specifications over the implementation. In particular, it defines the user profile data model related to this service. o section 3.1 of [I-D.ietf-bliss-problem-statement] includes some examples of call forwarding. 3.4. Specifications o RFC4458 [RFC4458] specifies two new parameters for the contact field that could be added when a call is forwarded. These parameters are 'cause' and 'target': they allow voicemails, for instance, to send an adapted greeting to the caller who has been transferred. RFC4244 [RFC4244] introduces a new optional header: 'history-info' which contains the list of previous target URIs of the call and could contain additional values such as the cause of each call forwarding, levels of privacy, etc. o TS183 004 [TS183004] from TISPAN shows how to use a centralized server for holding configuration and how to allow users to manage their profile and configurations. o RFC 3880 [RFC3880], CPL, presents a language which can be used by users in this context in order to upload rules of call forwarding to their proxy. The proxy should interpret this set of rules and apply them without any action from the endpoint. Ligot & Froment Expires May 12, 2008 [Page 7] Internet-Draft SIP Services Guide November 2007 o Like CPL, LESS [I-D.wu-iptel-less] is a language that could be used to configure call forwarding but on the terminal side. o RFC 3841 [RFC3841] could be used to register fall back destination for a user. It could also be used to register UA like voicemail. o As call forwarding often comes with privacy requirements, RFC3323 [RFC3323] could be helpful but it also introduces some requirements over the networks' infrastructure. Ligot & Froment Expires May 12, 2008 [Page 8] Internet-Draft SIP Services Guide November 2007 4. Call Transfer 4.1. Description Call transfer occurs when a communication is already established between parties and one of them, the transferor, wants to transfer the other party, the transferee, to another party, the target, which is not already a member of the dialog. Requirements for this services often include privacy and authentication. The target of a transfer could be a service, a conference room, or something else... Transfer could be managed. In this case, the transferor invites the target, establishes a communication with it while the other party is usually on hold and then ends its communication with it. Finally, it transfers the tranferee to the target. 4.2. Frameworks and requirements o Section 4 of cc-transfer [I-D.ietf-sipping-cc-transfer] gives requirements of the service. 4.3. Call flows samples o Section 4, 5 and 6 of service-examples [I-D.ietf-sipping-service-examples] present some call flows using REFER or MESSAGE in order to initiate the transfer. o draft-ietf-sipping-cc-transfer [I-D.ietf-sipping-cc-transfer] gives more details about transfer using REFER. This draft shows a lot of different cases using for example RFC3323 [RFC3323]. Call flows of TISPAN, TS183 029 [TS183029], are nearly the same. 4.4. Specifications o RFC 3515 [RFC3515] specifies the REFER method which allows a terminal to ask another terminal to send another SIP request. This is the most commonly used method for making transfer. o When the target receives the REFER request, it sends, in most cases, an INVITE to the transferee. The transferee SHOULD accept this INVITE. RFC 3891 [RFC3891] and RFC 4538 [RFC4538] introduce new headers which allow the transferee to know that the new INVITE is related to another dialog. RFC 3892 [RFC3892] lets it know who sent the REFER. RFC3893 [RFC3893] allows to sign these informations. Ligot & Froment Expires May 12, 2008 [Page 9] Internet-Draft SIP Services Guide November 2007 o REFER implies an event package, RFC 3265 [RFC3265], that can be suppressed using RFC 4488 [RFC4488]. This event package allows the transferor to get information about the status of the transfer. INVITE can also imply events as specified in RFC4235 [RFC4235]. o In order to prevent the INVITE generated by the REFER to reach all terminals of the transferee, GRUU [I-D.ietf-sip-gruu] allows to get a direct address to the user agent concerned by the new INVITE. o Presence [RFC3856] could be a source of information about the status of one user which can help application to define next target of a call. o Users may desire to initiate a transfer which is not managed by their terminal. In this case RFC 4730 [RFC4730] allows intermediaries to receive events from the keypad of the user's terminal. o Like with RFC 3840 [RFC3840] and RFC 3841 [RFC3841], capabilities of the target could be received by the transferor using RFC 4508 [RFC4508]. o Privacy [RFC3323]i is also a basic requirement for this service. Ligot & Froment Expires May 12, 2008 [Page 10] Internet-Draft SIP Services Guide November 2007 5. Hold 5.1. Description Justification of this service is that it is often useful to prevent the other party from listening to the conversation for a short period. Instead of hearing the other party, the party on hold could hear a music. Moreover, the terminal on hold SHOULD know it is on hold in order to give a correct feedback to the user. 5.2. Frameworks and requirements none found 5.3. Call flows samples o section 1, 2 and 3 of service-examples [I-D.ietf-sipping-service-examples] present some call flow cases of hold. o TS183 010 [TS183010] from TISPAN use similar call flows. 5.4. Specifications o Call flows showed in both documents in previous section use RFC 3725 [RFC3725], 3PCC, in order to change SDP parameters of the call. o If music has to be sent from a server, a media server MAY be needed, this is partially defined into RFC4240 [RFC4240]. Ligot & Froment Expires May 12, 2008 [Page 11] Internet-Draft SIP Services Guide November 2007 6. Call Baring 6.1. Description Users SHOULD be able to block, or make any preventive action on unsolicited calls based on a set of rules. This service could be executed either on the endpoint or on an intermediary server. Service provider could also be interested in setting a set of rules on top of users ones. 6.2. Frameworks and requirements o draft-froment-sipping-spit-requirements [I-D.froment-sipping-spit-requirements]. This document defines a set of requirements to define policies allowing to make any kind of reactive actions to prevent SPIT. o draft-tschofenig-sipping-framework-spit-reduction [I-D.tschofenig-sipping-framework-spit-reduction]. This document describes a framework for the usage of SPIT policies. 6.3. Call flows samples none found 6.4. Specifications o spit-policy [I-D.tschofenig-sipping-spit-policy]. This is a policy document format specification proposal for the requirements defined in draft-froment-sipping-spit-requirements [I-D.froment-sipping-spit-requirements]. This can be used to implement Call barring, but scope is larger since it can be used to make white or black lists, or to have different reactive actions (block, polite block, ask for a Turing test, ask for consent, send an email...), depending on the policies. o acr-code [I-D.ietf-sip-acr-code] defines criteria which can be used to reject calls: Privacy [RFC3323], using P-Asserted-Identity header [RFC3325] or by reading the content of From header. It also defines an error code: 433. o TS183 011 [TS183011] defines the service data model to be put on an application server and introduces a set of rules, based on Initial Filter Criterias (IFC) specified into TS183 033 [TS183033]. o CPL [RFC3880] and LESS [I-D.wu-iptel-less] allow users to write down a set of rules, which are stored on a server for the first Ligot & Froment Expires May 12, 2008 [Page 12] Internet-Draft SIP Services Guide November 2007 one, and in user's terminal for the second one. Ligot & Froment Expires May 12, 2008 [Page 13] Internet-Draft SIP Services Guide November 2007 7. Conference 7.1. Description Conference allows more than two peoples to speak together. It may also provide users with some features like allowing to invite somebody inside the conference or moderate the room, ... Most of these requirements are very well defined into RFC 4245 [RFC4245] 7.2. Frameworks and requirements o RFC4245 [RFC4245] only defines which conferencing requirements are expected from users. o RFC4353 [RFC4353] does not specify any service but terms, roles, actions of each participant, user, software. o RFC4597 [RFC4597] presents some scenarios of conference which could lead to some problems unless followed carefully. 7.3. Call flows samples o section 10 and 11 of service-examples [I-D.ietf-sipping-service-examples] show some very basics call flows of conferencing. 7.4. Specifications o RFC 4575 [RFC4575] allows users to get information over the current room by defining an event package. When a user joins a room, he could, for example, subscribe to this event package and receive notifications when somebody else join this room. uri- list-conferencing [I-D.ietf-sip-uri-list-conferencing] gives another way to publish his URI while joining the conference and allows other users to retrieve the list of members of the current room. conference-list-event [I-D.koren-sipping-conference-list-event] presents another list of events related to conferences. o RFC 4579 [RFC4579] explains how to add or remove somebody from a conference room by using REFER/INVITE or REFER/BYE. It also explains how to create a conference room using an INVITE and how headers like Join [RFC3911] or Replace [RFC3891] SHOULD be used. This document also presents features allowing users to change their User Agents without leaving the room or allowing users to convert simple dialog with two parties into a conference. As adding somebody inside a conference is basically a transfer, there is more documentation of this in the "Transfer" section above. Ligot & Froment Expires May 12, 2008 [Page 14] Internet-Draft SIP Services Guide November 2007 o While members of a room MAY NOT have the same capabilities depending on their user agent, conference server should be able to do transcoding. This is specified into:transc-conf [I-D.ietf-sipping-transc-conf] and [I-D.ietf-sipping-transc-framework]. o TS183 005 [TS183005] from TISPAN uses specifications from IETF. This document does not include any reference to RFC 4575 [RFC4575] o RFC4240 [RFC4240] defines media servers and how they can be used for making announcements. RFC 5022 [RFC5022] explains how to control them. o Even if RFC 3550 [RFC3550] is not directly related to SIP, it specifies how RTP streams could be mixed. o adhoc-conferencing [I-D.camarillo-sipping-adhoc-conferencing] gives specifications for using servers in ad-hoc mode. Ligot & Froment Expires May 12, 2008 [Page 15] Internet-Draft SIP Services Guide November 2007 8. Call parking 8.1. Description Call parking allows users to put a call on hold, hang up his terminal and retrieve the call from this terminal or from another terminal using a unique URI. 8.2. Frameworks and requirements none found 8.3. Call flows samples o sections 15 and 16 of service-examples [I-D.ietf-sipping-service-examples] show some very basic call flows of conferencing. 8.4. Specifications o A first specification of call parking could be found into: draft-procter-bliss-call-park-extension [I-D.procter-bliss-call-park-extension]. o Call parking could be considered as equivalent to two transfers to a kind of conference room. In that case, specifications described above could be reused. o The call which is parked could be considered as 'on hold'. Ligot & Froment Expires May 12, 2008 [Page 16] Internet-Draft SIP Services Guide November 2007 9. Do not disturb 9.1. Description This service should allow users to prevent temporary calls from one or all users from disturbing him. This means he does not want INVITE messages matching pre-defined rules to make his terminal ring because he will not answer. There is, at the present time, no particular specification. (other than sending an error message from RFC 3261 [RFC3261], for example, to the caller). However a draft: draft-elwell-bliss-dnd-00 [I-D.elwell-bliss-dnd] gives an analysis of the current situation. 9.2. Frameworks and requirements none found 9.3. Call flows samples none found 9.4. Specifications none found Ligot & Froment Expires May 12, 2008 [Page 17] Internet-Draft SIP Services Guide November 2007 10. Call Completion 10.1. Description TBC 10.2. Frameworks and requirements TBC 10.3. Call flows samples TBC 10.4. Specifications poetzl-bliss-call-completion [I-D.poetzl-bliss-call-completion] proposes a specification where the service is implemented thanks to a new event package. Ligot & Froment Expires May 12, 2008 [Page 18] Internet-Draft SIP Services Guide November 2007 11. Conclusion This first version shows that specifications are actually numerous. It also shows that there is a lack of framework and requirements. Information is difficult to find, and is sometimes hidden in individual contributions which are not always understood by non-IETF people as "unofficial". It MAY partially explain why SIP services implementors are not always satisfied and it clearly does not help interoperability. That's why this document was created. Some external references, like the TISPAN specification have a different objective and are difficult to compare since they take some assumptions on the network architecture, but they still sometimes contain protocol requirements that MAY be impact protocol specifications. It is today an open issue to decide if this document should address features out of BLISS working group scope... Ligot & Froment Expires May 12, 2008 [Page 19] Internet-Draft SIP Services Guide November 2007 12. IANA Considerations This document does not require any actions by IANA. Ligot & Froment Expires May 12, 2008 [Page 20] Internet-Draft SIP Services Guide November 2007 13. Security Considerations TBC Ligot & Froment Expires May 12, 2008 [Page 21] Internet-Draft SIP Services Guide November 2007 14. Acknowledgments Ligot & Froment Expires May 12, 2008 [Page 22] Internet-Draft SIP Services Guide November 2007 15. References 15.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. 15.2. Informative References [I-D.camarillo-sipping-adhoc-conferencing] Camarillo, G. and A. Johnston, "Ad-Hoc Conferencing in the Session Initiation Protocol (SIP)", draft-camarillo-sipping-adhoc-conferencing-00 (work in progress), March 2004. [I-D.elwell-bliss-dnd] Elwell, J. and M. Vakil, "An Analysis of Do Not Disturb (DND) Implementations in the Session Initiation Protocol (SIP)", draft-elwell-bliss-dnd-00 (work in progress), June 2007. [I-D.froment-sipping-spit-requirements] Froment, T., "Requirements for Authorization Policies to tackle Spam and Unwanted Communication for Internet Telephony", draft-froment-sipping-spit-requirements-01 (work in progress), July 2007. [I-D.ietf-bliss-problem-statement] Rosenberg, J., "Basic Level of Interoperability for Session Initiation Protocol (SIP) Services (BLISS) Problem Statement", draft-ietf-bliss-problem-statement-00 (work in progress), July 2007. [I-D.ietf-sip-acr-code] Rosenberg, J., "Rejecting Anonymous Requests in the Session Initiation Protocol (SIP)", draft-ietf-sip-acr-code-05 (work in progress), July 2007. [I-D.ietf-sip-gruu] Rosenberg, J., "Obtaining and Using Globally Routable User Agent (UA) URIs (GRUU) in the Session Initiation Protocol (SIP)", draft-ietf-sip-gruu-15 (work in progress), October 2007. [I-D.ietf-sip-uri-list-conferencing] Camarillo, G. and A. Johnston, "Conference Establishment Using Request-Contained Lists in the Session Initiation Protocol (SIP)", draft-ietf-sip-uri-list-conferencing-01 Ligot & Froment Expires May 12, 2008 [Page 23] Internet-Draft SIP Services Guide November 2007 (work in progress), January 2007. [I-D.ietf-sipping-cc-framework] Mahy, R., "A Call Control and Multi-party usage framework for the Session Initiation Protocol (SIP)", draft-ietf-sipping-cc-framework-07 (work in progress), March 2007. [I-D.ietf-sipping-cc-transfer] Sparks, R., "Session Initiation Protocol Call Control - Transfer", draft-ietf-sipping-cc-transfer-08 (work in progress), July 2007. [I-D.ietf-sipping-service-examples] Johnston, A., "Session Initiation Protocol Service Examples", draft-ietf-sipping-service-examples-13 (work in progress), July 2007. [I-D.ietf-sipping-transc-conf] Camarillo, G., "The Session Initiation Protocol (SIP) Conference Bridge Transcoding Model", draft-ietf-sipping-transc-conf-03 (work in progress), June 2006. [I-D.ietf-sipping-transc-framework] Camarillo, G., "Framework for Transcoding with the Session Initiation Protocol (SIP)", draft-ietf-sipping-transc-framework-05 (work in progress), December 2006. [I-D.koren-sipping-conference-list-event] Fortinsky, M. and O. Koren, "A Conference List Information Event Package for the Session Initiation Protocol (SIP)", draft-koren-sipping-conference-list-event-01 (work in progress), July 2007. [I-D.poetzl-bliss-call-completion] Poetzl, J., "Extensions to the Session Initiation Protocol (SIP) for the support of the Call Completion Services for the European Telecommunications Standards Institute", draft-poetzl-bliss-call-completion-00 (work in progress), July 2007. [I-D.procter-bliss-call-park-extension] Procter, M., "An approach to Call Park/Retrieve using SIP", draft-procter-bliss-call-park-extension-00 (work in progress), March 2007. Ligot & Froment Expires May 12, 2008 [Page 24] Internet-Draft SIP Services Guide November 2007 [I-D.tschofenig-sipping-framework-spit-reduction] Tschofenig, H., "A Framework to tackle Spam and Unwanted Communication for Internet Telephony", draft-tschofenig-sipping-framework-spit-reduction-01 (work in progress), July 2007. [I-D.tschofenig-sipping-spit-policy] Tschofenig, H., "A Document Format for Expressing Authorization Policies to tackle Spam and Unwanted Communication for Internet Telephony", draft-tschofenig-sipping-spit-policy-01 (work in progress), July 2007. [I-D.wu-iptel-less] Wu, X. and H. Schulzrinne, "LESS: Language for End System Services in Internet Telephony", draft-wu-iptel-less-00 (work in progress), February 2005. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [RFC3323] Peterson, J., "A Privacy Mechanism for the Session Initiation Protocol (SIP)", RFC 3323, November 2002. [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks", RFC 3325, November 2002. [RFC3515] Sparks, R., "The Session Initiation Protocol (SIP) Refer Method", RFC 3515, April 2003. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo, "Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)", BCP 85, RFC 3725, April 2004. [RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating User Agent Capabilities in the Session Ligot & Froment Expires May 12, 2008 [Page 25] Internet-Draft SIP Services Guide November 2007 Initiation Protocol (SIP)", RFC 3840, August 2004. [RFC3841] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Caller Preferences for the Session Initiation Protocol (SIP)", RFC 3841, August 2004. [RFC3856] Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", RFC 3856, August 2004. [RFC3880] Lennox, J., Wu, X., and H. Schulzrinne, "Call Processing Language (CPL): A Language for User Control of Internet Telephony Services", RFC 3880, October 2004. [RFC3891] Mahy, R., Biggs, B., and R. Dean, "The Session Initiation Protocol (SIP) "Replaces" Header", RFC 3891, September 2004. [RFC3892] Sparks, R., "The Session Initiation Protocol (SIP) Referred-By Mechanism", RFC 3892, September 2004. [RFC3893] Peterson, J., "Session Initiation Protocol (SIP) Authenticated Identity Body (AIB) Format", RFC 3893, September 2004. [RFC3911] Mahy, R. and D. Petrie, "The Session Initiation Protocol (SIP) "Join" Header", RFC 3911, October 2004. [RFC4235] Rosenberg, J., Schulzrinne, H., and R. Mahy, "An INVITE- Initiated Dialog Event Package for the Session Initiation Protocol (SIP)", RFC 4235, November 2005. [RFC4240] Burger, E., Van Dyke, J., and A. Spitzer, "Basic Network Media Services with SIP", RFC 4240, December 2005. [RFC4244] Barnes, M., "An Extension to the Session Initiation Protocol (SIP) for Request History Information", RFC 4244, November 2005. [RFC4245] Levin, O. and R. Even, "High-Level Requirements for Tightly Coupled SIP Conferencing", RFC 4245, November 2005. [RFC4353] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol (SIP)", RFC 4353, February 2006. [RFC4458] Jennings, C., Audet, F., and J. Elwell, "Session Initiation Protocol (SIP) URIs for Applications such as Ligot & Froment Expires May 12, 2008 [Page 26] Internet-Draft SIP Services Guide November 2007 Voicemail and Interactive Voice Response (IVR)", RFC 4458, April 2006. [RFC4488] Levin, O., "Suppression of Session Initiation Protocol (SIP) REFER Method Implicit Subscription", RFC 4488, May 2006. [RFC4508] Levin, O. and A. Johnston, "Conveying Feature Tags with the Session Initiation Protocol (SIP) REFER Method", RFC 4508, May 2006. [RFC4538] Rosenberg, J., "Request Authorization through Dialog Identification in the Session Initiation Protocol (SIP)", RFC 4538, June 2006. [RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006. [RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol (SIP) Call Control - Conferencing for User Agents", BCP 119, RFC 4579, August 2006. [RFC4597] Even, R. and N. Ismail, "Conferencing Scenarios", RFC 4597, August 2006. [RFC4730] Burger, E. and M. Dolly, "A Session Initiation Protocol (SIP) Event Package for Key Press Stimulus (KPML)", RFC 4730, November 2006. [RFC5022] Van Dyke, J., Burger, E., and A. Spitzer, "Media Server Control Markup Language (MSCML) and Protocol", RFC 5022, September 2007. [TS183004] "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN);PSTN/ISDN simulation services: Communication Diversion (CDIV);Protocol specification", 2007. [TS183005] "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); PSTN/ISDN simulation services: Conference (CONF); Protocol specification", 04 2007. [TS183010] "Telecommunications and Internet converged Services and Ligot & Froment Expires May 12, 2008 [Page 27] Internet-Draft SIP Services Guide November 2007 Protocols for Advanced Networking (TISPAN);NGN Signalling Control Protocol;Communication HOLD (HOLD) PSTN/ISDN simulation services;Protocol specification", 2007. [TS183011] 7, "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN);PSTN/ISDN simulation services: Anonymous Communication Rejection (ACR) and Communication Barring (CB);Protocol specification", 2007. [TS183029] "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN);PSTN/ISDN simulation services: Explicit Communication Transfer (ECT);Protocol specification", 2007. [TS183033] "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN);IP Multimedia;Diameter based protocol for the interfaces between the Call Session Control Function and the User Profile Server Function/Subscription Locator Function;Signalling flows and protocol details [3GPP TS 29.228 V6.8.0 and 3GPP TS 29.229 V6.6.0, modified]", 2007. Ligot & Froment Expires May 12, 2008 [Page 28] Internet-Draft SIP Services Guide November 2007 Authors' Addresses Arnaud Ligot Alcatel-Lucent Centre de Villarceaux, Route de Villejust Nozay, Paris 91620 France Email: Arnaud.Ligot@alcatel-lucent.fr Thomas Froment Alcatel-Lucent Centre de Villarceaux, Route de Villejust Nozay, Paris 91620 France Email: Thomas.Froment@alcatel-lucent.fr Ligot & Froment Expires May 12, 2008 [Page 29] Internet-Draft SIP Services Guide November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Ligot & Froment Expires May 12, 2008 [Page 30]