No voice path on internet phone

We have an LG Ericsson iPecs ES2026P and UCP100 system which connects with the internet via a Technicolor MediaAccess TG588v router/modem. The ISP at this end is TalkTalk via Toople.

We have a phone which seeks to communicate with the system over the internet via a TP-Link TD-W8968 router.

The two machines can talk to each other, and can make calls, but there is no audio path: neither party can hear anything. The MediaAccess router has been set up with the recomended ports open and SIP ALG off.

Any ideas?

Problem solved!
Router needed an update to allow blocks of ports to be forwarded.
Many thanks to LinkDJ

Edited by deleted (Fri 03-Feb-17 18:21:07)