RFC 3486:Compressing the Session Initiation Protoc...
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TCP


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... transport protocol to be used by SIP (e.g., UDP, TCP or SCTP). A SIP ...
... would grow dramatically. A server that, for example, supported TCP and SCTP as transports, TLS ...
... DNS entries listed below: 1. TCP, no security, no compression ...
... compression 2. TCP, no security, SigComp ...
... SigComp 3. TCP, TLS, no compression ...
... compression 4. TCP, TLS, SigComp ...
... port for TLS on top of TCP than for TCP alone, although at present, this solution is not considered scalable any longer. ...
... port for TLS on top of TCP than for TCP alone, although at present, this solution is not considered scalable any longer. ...


... retry the same request without using compression. If the compressed request was sent over a TCP connection, the client SHOULD close that connection ...



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