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