Outbound (RFC 5626)

OverSIP implements the RFC 5626 “Managing Client-Initiated Connections in SIP” (as a SIP proxy). This feature works for any kind of SIP transport (UDP, TCP, TLS, WS, WSS) and allows clients behind NAT to properly intercommunicate at SIP level without performing “hacks” like “Contact URI mangling”.

OverSIP automatically becomes an Outbound Edge Proxy when a SIP client asks for Outbound assistance, but such a behaviour can also be forced via the fix_nat() method of the OverSIP::SIP::Request class for legacy SIP clients not implementing the Outbound specification.

RFC 5626

OverSIP implements the following items of RFC 5626 “Managing Client-Initiated Connections in SIP” (Outbound):

• Edge Proxy Procedures: section 3.4 and section 5
• Keep-Alive Technique (CRLF Keep-Alive and STUN Keep-Alive): section 3.5 and section 8