Multiple Dialog Usages in the Session Initiation Protocol

Session Initiation Protocol (SIP) Response Code for Indication of Terminated Dialog

“…If multiple usages [RFC5057] are used within an early dialog, and it is not clear which dialog usage the 199 response terminates, SIP entities that keep dialog state SHALL NOT release resources associated with the early dialog when they receive the 199 response.…”

Session Initiation Protocol (SIP) Call Control - Transfer

“…However, the approach described in this document is to avoid dialog reuse. The issues and difficulties associated with dialog reuse are described in [RFC5057].…”

Request Authorization through Dialog Identification in the Session Initiation Protocol (SIP)

“…This specification is based on a header field first proposed by Robert Sparks in the dialog usage draft [12]. John Elwell provided helpful comments.…”

“…Current implementations deal with this by sending the REFER on the same dialog as the one in place between user agents A and B. However, this approach has numerous problems [12]. These problems include difficulties in determining the lifecycle of the dialog and its usages and in determining which messages are associated with each application usage.…”