No audio when changed internet connection

Hello all, hoping someone could help.
We have changed internet providers and router, all internal phones can communicate and work fine.
Offsite phones have been updated to the new IP address and have registered fine, however there is no audio when calling there extension. using both Yealink VOIP phone and an analogue phone connected via Linksys Adapter.
I took a screen shot of the port forwarding from previous router and matched exactly the same with the new one, i have made the router the same local IP address as the old router.
Running Freepbx 2.11. Not sure what other information you need as im new to freepbx.


Browse to Settings, Asterisk SIP settings and make sure you’ve updated to your new external WAN IP.