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.