Cisco 7960 Phones have no audio in either direction on Inbound calls

We are using a hosted FreePBX provider. We have Cisco SPA504G phones working fine with this provider. However, our 7960s will only make outbound calls with no issue. Any Inbound call that goes to a 7960 (answered on ring or transferred from a 504) has no audio in either direction. The calls stay connected and timers run as if the call is live, but there is no audio at all.

We’ve confirmed all the ports on the firewall are wide open as we have a trusted connection to the FreePBX Hosted provider and our office.

Any help is appreciated.