I have just finished setting up an installation. I am not using any TDM hardware so no zaptel drivers in use here. Here is the layout of installation.
analogue phone<------>Grandstream ATA-486 <–LAN—>Asterisk<—LAN—>ADSL router<—Internet—>sipgate.co.uk<----PSTN---->Regular phone
No NAT is involved I am using public IP addresses for the grandstream and the asterisk server.
Locally originated and terminated calls on the Asterisk server are fine but calls via sipgate result in a large echo on the Grandsteam end it doesn’t matter if the call in inbound or outbound.
All the references to echo reduction refer to the use of zaptel driver configuration to reduce this I cant seem to find out how to reduce or elimate this issue when you are not using TDM hardware.
I am migrating from just using sipgate directly as follows.
analogue phone<------>Grandstream ATA-486 <–LAN—>ADSL router<—Internet—>sipgate.co.uk<----PSTN---->Regular phone
I was not experiencing the echo with this config.
Any ideas appreciated