issue with internal calls

[bunter12345]

I have a strange issues with internal calls, all outbound calls work OK and I can hear speech both ways, when I phone from a Yealink T28 to a Cisco SPA504G internally, the phone rings and answers OK but there is no speech either way. Both phones can make outbound calls fine.

The system is configured in a datacentre and both handsets are connected as remote sip extensions to the 3CX system at the datacentre. All ports are open and everything else works ok.

The only thing I can see is that the extensions that I am trying to call between are on the same remote IP address but I cannot see that this would be the issue as this is how we would configure the system where all phones are behind the same IP address.

Any help or advice would be greatly appreciated.

Thanks

 

[leejor]

You can try enabling the option "PBX delivers audio" on each extension. That may fix the issue in the meantime. You're not the first to have audio issue between remote extensions, behind the same router, unfortunately, there is no one solution. It could be the particular router, the settings in the router, or the configuration in the set(s).

I assume that each set has been assigned a unique ports number so that there are no conflicts. If available, you might try swapping out the router for a different model, or see if there are any SIP ALG settings that require changes. In many remote extension locations, the 3CX SBC is deployed to help avoid this sort of thing (and not requite that audio always pass back to, and through, the PBX), however, if only two extensions are involved it is a bit of an overkill.