I have PBX with SIP registrar running on 5060/UDP for the local users and non-standard port (say for example 6060) for remote. I have a problem with Windows 3CX client in the following scenario: I make i call from any local extension to the remote 3CX Client: host1.ip:6060 -> Invite -> host2.ip:5060 the client reply: host1.ip:6060 <- Ringing <- host2.ip:5060 answer the call: host1.ip:6060 <- OK <- host2.ip:5060 host1.ip:6060 -> ACK -> host2.ip:5060 now we a talking. All OK. And when 3cx client hang on, i can see: host1.ip:5060 <- BYE <- host2.ip:5060 The problem is that the 3CX Client sends a BYE request to the port 5060 instead of 6060. So the host1 is still on the line. Is it any possibility to fix this problem ? I use the option I am in the office - local IP anyway, but as i understand it doent matter ni my case.