Hello forum,

Innovaphone IP411 (version 13r1 sr8) is behind a router/firewall, with private IP address 10.0.0.240.

I'm working from home nowadays, and have successfully registered a hardphone (ip112) and a SIP-softphone (3cx).

The SIP-softphone directly connects to a PBX User Object (no Gateway SIP trunk involved).

When the softphone calls the hardphone, and the hardphone picks up, the 200 OK message (PBX > 3cx) contains the private ip address (10.0.0.240) in the Contact-header (<sip:65@10.0.0.240:5060;user=phone;transport=UDP>). As a result, the softphone wants to send the ACK to this private address, which fails. This "200 OK/ACK"-loop is repeated several times until one gives up.

My question : how to avoid that the SIP Contact header contains a private ip address?

IP4 > General > Settings > Private Networks is already configured with the 10.0.0.0 network (netmask 255.255.255.0)

I also tried to enable PBX > Config > General > Use as Domain

and configured PBX > Config > General > DNS

but without luck.

Screenshot of SIP trace is attached.

Thanks for your help,

Best regards,

Sam