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Folks, I work for a VoIP company, Level3 Communications, and have
been doing some research on the internet about a specific condition that has arisen here dealing with the
Sip protocol. Your names came up during my research. Was hoping I could get some feedback about the reuse of Sip
Call-Id. We have customer UAs that are reusing the same Sip Call-Id
for multiple call attempts into our network. After reviewing the Sip RFC 3261, both myself and my team
concluded that this was a clear violation of the spec. based on the following verbiage... 8.1.1.4 Call-ID The Call-ID header field acts as a unique identifier to
group together a series of messages. It MUST be the same for
all requests and responses sent by either UA in a dialog. It SHOULD
be the same in each registration from a UA. In a new request created by a UAC outside of any dialog,
the Call-ID header field MUST be selected by the UAC as a globally
unique identifier over space and time unless overridden by
method-specific behavior. All SIP UAs must have a means to guarantee
that the Call- ID header fields they produce will not be inadvertently
generated by any other UA. Note that when requests are retried after
certain However, some voice engineers are stating that the
definition of “globally unique over time and space” means only
during the context of a given call. Therefore, once this context is
over....Sip Call-Id can in fact be reused in the very next context. What is your take on this? Thanks, Glenn E. Cahall Sr. Architect Level3 Communications |