Zulu UC works on wifi but not on 4G

The Zulu UC mobile app is all setup and working*. Works fine when I am on wifi (PBX accessible over the WLAN). I can hear the caller, they can hear me. I have the server configured with Fqdn and port 8002 is opened.

When I’m on 4G or out of the office on another network, it rings but there is no audio at all on either end. I can ping the fqdn and have confirmed that 8002 is opened.

I personally use zulu on 4G (Verizon LTE) with Android and have no problems. It was actually one of my favorite things about the app when I first got it. I would consider maybe a provider issue. There is no good way to test this except try another provider.

This is probably good info to provide
Phone type/model

I am using an iPhone 8 Plus on Telus Mobility in Canada. We have a Sophos SG firewall but i’ve looked through all the rules and they are correct.

It may also be worth trying a VPN service for testing in case the traffic type is blocked. Again not by you but by Telus

Talking to some of our folks who are generally smarter than me, they think it could be the carrier giving you an IPv6 address. I would open a support ticket at https://support.sangoma.com so they can give it all a quick look.

I opened a ticket via support under FreePBX Support > FreePBX Commercial Modules > Zulu

http://test-ipv6.com/ tells me that my iPhone doesn’t have an IPv6 address. I also see the IPv4 address of my phone (Telus WAN IP) in the FreePBX Firewall under Registered Endpoints

Still nothing here…

I suspect that the 4G part of this is a red herring. When you are on Wifi, you are probably on a known network. If you are 4G, you aren’t necessarily. This could be a good old-fachioned NAT problem. Check your Adaptive Firewall settings and make sure you have everything set up correctly to get the traffic into the PBX. You might also need to check your external firewall and make sure that the port forwarding is set up correctly.

My external firewall is set to allow all traffic from anywhere for 8002

I’ve gone as far as add the Telus public IP that my iPhone is getting to the FreePBX firewall

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