Incomming calls not working

Hi. I have just installed freepbx. I have updated all my modules and configured a SIP Trunk to my ISP. I can successfully make outside calls and calls between extensions. I can’t receive any calls via my ISP SIP Trunk. FreePBX status shows that one trunk is online and registered.

If I setup my SIP Phone with the ISP SIP details I can make and receive calls, but it does not work through the PBX.

Can somebody direct me where to start my troubleshooting

You could start with

to get yourself past the normal misconfiguraes.