Q&A: SIP and SIP-I
What is session control?
What are some examples of session control protocols?
Does 3G Americas have a recommendation for session control protocol?
Why is SIP-I recommended?
Who should deploy SIP-I?
What is session control?
Session control refers to the process used to create, modify, and terminate IP-based communication sessions of various methods, including two-way voice communication, multimedia (text, audio, or video) conference collaboration, instant messaging, application sharing, and other contemplated but not yet fully specified services. It is accomplished through signaling between various network elements and endpoints using a session control protocol.
Return to top
What are some examples of session control protocols?
The most widely known session control protocol is Session Initiation Protocol (SIP). BICC is the current protocol standardized in 3GPP Release 4 architecture and deployed in some networks today. There are also variants to SIP with ISUP encapsulations known as SIP-I and SIP-T.
- BICC: Bearer Independent Call Control
- SIP: Session Initiation Protocol
- ISUP: ISDN User Part
- SIP-I: Session Initiation Protocol with encapsulated ISUP
- SIP-T: Session Initiation Protocol for Telephones
Return to top
Does 3G Americas have a recommendation for session control protocol?
3G Americas recommends to the wireless industry, and GSM/UMTS/LTE operators in particular, the adoption of a single session control protocol which will support the creation, modification and termination of packetized voice sessions in an existing GSM/UMTS or future LTE network. In a recent white paper (August 2007), Why SIP-I? A Switching Core Protocol Recommendation for GSM/UMTS Operators, 3G Americas recommends SIP-I based on analysis and comparison of three session control protocols that can inter-work with the PSTN: BICC, SIP-I and SIP-T.
Return to top
Why is SIP-I recommended?
HBICC is the current protocol standardized in the 3GPP Release 4 architecture and deployed in some networks today. However, BICC is not an optimal choice for ongoing evolution because it has been limited to, and is predicted to remain limited to, operation within a GSM/UMTS context. BICC does not address domains beyond GSM/UMTS such as LTE; as a result, it does not automatically offer the future level of flexibility of continued development and evolution that would accompany the SIP with ISUP encapsulation variants (i.e. either SIP-T or SIP-I).
The 3G Americas SIP-I white paper presents a detailed technical analysis of capabilities existing within the two SIP technologies with ISUP encapsulation variants, and provides the recommended direction for evolution: SIP-I. There are four areas where SIP-I is better suited for a GSM/UMTS environment than SIP-T:
- Assumptions regarding the trust and security environment.
- Encapsulation procedures & message mapping.
- Support of RFCs.
- User plane interoperability.
Return to top
Who should deploy SIP-I?
3G Americas recommends that all GSM/UMTS network operators put SIP-I on their network evolution roadmap as the session control protocol, and, as operational requirements and service delivery requirements emerge, and evolve to SIP-I technology over time.
Return to top
Return to Questions and Answers home page
| 
