Completion of Calls for the Session Initiation Protocol (SIP)

Abstract

The "completion of calls" feature defined in this specification allows the caller of a failed call to be notified when the callee becomes available to receive a call. For the realization of a basic solution without queuing, this document references the usage of the dialog event package (RFC 4235) that is described as 'Automatic Redial' in "Session Initiation Protocol Service Examples" (RFC 5359). For the realization of a more comprehensive solution with queuing, this document introduces an architecture for implementing these features in the Session Initiation Protocol where "completion of calls" implementations associated with the caller's and callee's endpoints cooperate to place the caller's request for completion of calls into a queue at the callee's endpoint; when a caller's request is ready to be serviced, re-attempt of the original, failed call is then made. The architecture is designed to interoperate well with existing completion of calls solutions in other networks. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6910.

URNs for the Alert-Info Header Field of the Session Initiation Protocol (SIP)

“…This feature is used when a user has utilized a server to implement an automatic callback service [RFC6910]. When the user is available, the server calls back the user and utilizes this service tone to distinguish this INVITE from a normal incoming call.…”