I do implementation in which PBXs are connected to Cisco routers using E&M ports at several sites. A FAX machine is connected to an extension on the PBX needs to communicate with another FAX machine connected to the PBX at another site. The settings of the E&M ports are here:
timing wait-wink 800
A voip dial-peers are configured for the destination router.
dial-peer voice 95 voip
session target ipv4:192.168.125.2
I tried some chnages but it did not work. I will try to configure the codec to G711 and no VAD and no EC on all ports and test it. But it will cost bandwidth.