No audio received by WAN client

So, everything works flawlessly on LAN. My issue occurs when I use my mobile client (zoiper) on an android phone on a 4g network (WAN)

I have changed the port from 5060 to one of my liking, we will use 6050 for this example. I have also narrowed down the RTP port to 17000-18000

WAN client connects, registers, and is able to receive inbound calls, whether routed from a trunk or another extension. It transmits audio fine as the other party can hear me without issue. However I cannot hear them. I check statistics and it shows 0b received. Now I suspect this is a fire walling issue either on the 4G end (Verizon) or by my firewall in front of my PBX.

Any ideas/suggestions?

Usually port blocking on the RTP ports, where did you restrict the ports, at the router or both the router and FPBX?

There’s a setting for the extension to force_rport, enabling this seems to work. But now I can’t get srtp/TLS to work on either LAN or WAN. I have alot of research to do here yet.

I guess I could just keep assuming while you avoid my question… good luck with it.

I don’t know which Firewall you are using but in a pfSense box, we used to have to set static ports on outbound NAT rules to get proper audio.