I´m using Zoiper successfuly to make and receive calls, when caller and callee are behind a NAT device. That is, bouth are in the same local network. My SIP Proxy (Registrar) is behind the same NAT.
When the caller moves to Internet, just the callee and SIP Proxy remain behind the NAT. For this case, I use to configure the default stun server (stun.zoiper.com) for the softphone. When I do this, I see (via wireshark) that softphone and stun server exchange messages. So, the configuration is Ok, I suppose.
However, even using the stun server,the Zoiper still registers itself using the private IP. That is, the Contact header field of SIP REGISTER has the private IP and not the public one.
How to configure Zoiper apropriately so that it will register in the SIP Proxy considering the public IP for sure?
Any hint will be very helpful!