Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)
RFC 3725
Document | Type |
RFC - Best Current Practice
(April 2004; No errata)
Also known as BCP 85
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Authors | Jon Peterson , Jonathan Rosenberg , Henning Schulzrinne , Gonzalo Camarillo | ||
Last updated | 2015-10-14 | ||
Replaces | draft-rosenberg-sip-3pcc | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3725 (Best Current Practice) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Allison Mankin | ||
Send notices to | <rohan@cisco.com>, <dean.willis@softarmor.com> |
Network Working Group J. Rosenberg Request for Comments: 3725 dynamicsoft BCP: 85 J. Peterson Category: Best Current Practice Neustar H. Schulzrinne Columbia University G. Camarillo Ericsson April 2004 Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP) Status of this Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract Third party call control refers to the ability of one entity to create a call in which communication is actually between other parties. Third party call control is possible using the mechanisms specified within the Session Initiation Protocol (SIP). However, there are several possible approaches, each with different benefits and drawbacks. This document discusses best current practices for the usage of SIP for third party call control. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3 4. 3pcc Call Establishment . . . . . . . . . . . . . . . . . . 3 4.1. Flow I . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Flow II. . . . . . . . . . . . . . . . . . . . . . . . 5 4.3. Flow III . . . . . . . . . . . . . . . . . . . . . . . 7 4.4. Flow IV. . . . . . . . . . . . . . . . . . . . . . . . 8 5. Recommendations . . . . . . . . . . . . . . . . . . . . . . 9 6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 10 7. Continued Processing . . . . . . . . . . . . . . . . . . . . 11 8. 3pcc and Early Media . . . . . . . . . . . . . . . . . . . . 13 Rosenberg, et al. Best Current Practice [Page 1] RFC 3725 SIP 3pcc April 2004 9. Third Party Call Control and SDP Preconditions . . . . . . . 16 9.1. Controller Initiates . . . . . . . . . . . . . . . . . 16 9.2. Party A Initiates. . . . . . . . . . . . . . . . . . . 18 10. Example Call Flows . . . . . . . . . . . . . . . . . . . . . 21 10.1. Click-to-Dial. . . . . . . . . . . . . . . . . . . . . 21 10.2. Mid-Call Announcement Capability . . . . . . . . . . . 23 11. Implementation Recommendations . . . . . . . . . . . . . . . 25 12. Security Considerations. . . . . . . . . . . . . . . . . . . 26 12.1. Authorization and Authentication . . . . . . . . . . . 26 12.2. End-to-End Encryption and Integrity. . . . . . . . . . 27 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 14.1. Normative References . . . . . . . . . . . . . . . . . 28 14.2. Informative References . . . . . . . . . . . . . . . . 29 15. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 30 16. Full Copyright Statement . . . . . . . . . . . . . . . . . . 31 1. Introduction In the traditional telephony context, third party call control allows one entity (which we call the controller) to set up and manage a communications relationship between two or more other parties. Third party call control (referred to as 3pcc) is often used for operator services (where an operator creates a call that connects two participants together) and conferencing. Similarly, many SIP services are possible through third party call control. These include the traditional ones on the PSTN, but also new ones such as click-to-dial. Click-to-dial allows a user to click on a web page when they wish to speak to a customer service representative. The web server then creates a call between the user and a customer service representative. The call can be between two phones, a phone and an IP host, or two IP hosts. Third party call control is possible using only the mechanisms specified within RFC 3261 [1]. Indeed, many different call flows are possible, each of which will work with SIP compliant user agents. However, there are benefits and drawbacks to each of these flows. The usage of third party call control also becomes more complex when aspects of the call utilize SIP extensions or optional features ofShow full document text