SIP sending internal IP instead of Public

[c.keen]

This sounds like the same issue that I was running in to. Make sure that your Firewall rules going from 3CX out are not being NAT'd. My PBX vendor was saying the same thing and I couldn't for the life of me figure out why it was sending the internal IP rather than the Public IP. Just a thought.

 

[lneblett]

What make and model of router? Some of the earlier model TP-LInk business class units would mangle the SIP headers and there was never a cure put into production.