Interface address used for sending/receiving packets to/from the session originator
$ifsrc = IP address or FQDN
It is an interface address used for sending/receiving the packets to/from the session originator (UAC). This address is used for the values in Via, Record-Route headers.
$ifsrc = 192.168.1.200
Set 192.168.0.100 as an interface address for the sending packets to the session originator.