Outbound Proxy
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... need a means to obtain a comp=sigcomp URI from their outbound proxy
before the user decides to establish a session.
...
... URI parameters. In this case, the client SHOULD send an
uncompressed OPTIONS request to its outbound proxy. The outbound
proxy can provide an alternative SIP URI with the comp=sigcomp ...
... client SHOULD send an
uncompressed OPTIONS request to its outbound proxy. The outbound
proxy can provide an alternative SIP URI with the comp=sigcomp
...
... client can use this URI for subsequent requests that
are sent through the same outbound proxy using compression.
...