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


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... above. The call flow of Figure 1 shows an INVITE-200 OK-ACK handshake between a UAC ...
... |(6)200 OK(c) |<------------| | |<------------| | | | | (7)ACK(c) | | |-------------------------->| (8) ACK | ...
... | | (7)ACK(c) | | |-------------------------->| (8) ACK | | | |------------>| | | | | ...
... sigcomp parameter. (7) ACK UAS Via: UAC ...
... The UAC sends the ACK (7) compressed directly to P2 (P1 did not Record-Route). ...
... Record-Route). (8) ACK UAS Via: P2 ...
... sigcomp P2 sends the ACK (8) uncompressed to the UAS. ...



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