Branch handling in Opensips
Branch route is an outbound route to handle the SIP requests leaving OpenSIPS can be used only with TM module since setting a branch route is per request/transaction
used in SIP forking scenarios—parallel or serial forking ( ie an incoming request branches to multiple outgoing requests ) Branch route gives you individual access to each outgoing branch.
Branch route is executed inside the t_relay() function, which is the one sending out the SIP branches on the network