| Summary: |
The Session Initiation Protocol (SIP) operates over UDP and TCP. When
used with UDP, responses to requests are returned to the source
address the request came from, but from the port written into the
topmost Via header of the request. This behavior is not desirable in
many cases, most notably, when the client is behind a NAT. This
extension defines a new parameter for the Via header, called rport,
that allows a client to request that the server send the response
back to the source IP address and port where the request came from.
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