drwats1

Sorry I may not have explained this properly. For years the zyxel internal fxs port has worked fine. Then we start getting no outgoing audio on outbound calls, after a firmware upgrade. The SiP ALG is turned off by standard. Incoming calls to the fxs port work fine. So far all we have from ISP and IP-PBX manufacturer is…

You would think so. The thing that has me confused is that the fault is only present on outgoing calls. We know it is something to do with the built-in ATA, as an external ATA works fine. Can inband signalling be switched on and off on the router?

When a call is made in - all works fine. When the call is made out there is no audio outbound from the router. Can't share logs I'm afraid