Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This document states requirements for a standardized SIP registration mechanism for multiple addresses of record (AORs), the mechanism being suitable for deployment by SIP service providers on a large scale in support of small to medium sized Private Branch Exchanges (PBXs). The requirements are for a solution that can, as a minimum, support AORs based on E.164 numbers.
The Session Initiation Protocol (SIP) has a mechanism for conveying the identity of the originator of a request by means of the P-Asserted-Identity and P-Preferred-Identity header fields. These header fields are specified for use in requests using a number of SIP methods, in particular the INVITE method. However, RFC 3325 does not specify the insertion of the P-Asserted-Identity header field by a trusted User Agent Client (UAC), does not specify the use of P-Asserted-Identity and P-Preferred-Identity header fields with certain SIP methods such as UPDATE, REGISTER, MESSAGE, and PUBLISH, and does not specify how to handle an unexpected number of URIs or unexpected URI schemes in these header fields. This document extends RFC 3325 to cover these situations.
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