Hello, I'm using Kamailio as SIP proxy to receive INVITE packets, randomize A-number and then relay it to a certain gateway. I noticed that a Via header is added to the INVITE sent by Kamailio to the gateway with 0.0.0.0 as address as shown below: Via: SIP/2.0/UDP 0.0.0.0;branch=z9hG4bK2d97.61de75dd58fa7ca7450cc8b9b01db62f.0 As far as I know, the IP that should be used in the new added VIA header must be Kamailio IP, but it's not the case here, knowing that Kamailio is not behind NAT. Regards, Ali Taher