What does rport without port number mean in SIP
When you have a SIPĀ Via:
header like
Via: SIP/2.0/UDP 95.117.121.206:18050;rport;branch=z9hG4bKabc123
theĀ rport
parameter means respond to the port from which the request was received
This is extremely useful in case of NAT traversal because you don’t know upfront which outgoing NAT port your packets will be mapped to.