I have one asterisk server on which i am running pbx, another asterisk server on which i have installed TDM2400P and deployed 4 lines.
I have made SP trunking between pbx server and TDM2400P server, so that call made from pbx will go out from my PSTN line and incoming also lands on pbx server.
There is problem when we make call on any pstn number we hear our own voice back, however it does not happen when we call on mobile number. We have also configure Dlink Hard phone DPH400SE. Our voice only echo when we call land line number. Please let me know if I need to do some changes.
Mobile networks and VoIP systems have large enough round trip delays that echo is objectionable, so the mobile network/phone is forced to do echo cancellation.
Once you introduce a VoIP phone into a standard PSTN environment, the time delay on the PSTN echo becomes objectionable. Except on internalational calls, the PSTN would not normally need to do echo cancellation. That’s why you are seeing these combinations behaving in these ways.
You do not have echo cancellation enabled, you have inadequate cancellation. If the cards support it, enabling cancellation in the hardware is best.
If the cards are new, you should be able to get support from the vendor. This forum is not a vendor support one.