Why my correspondents hear an echo when they speak

Question

I am using free Zoiper for long on my Mac.

Since few weeks, my correspondents that are using either land lines or mobiles hear themselves while talking to me. There is echo.

On my side ( with Zoiper), no problem at all, no echo. There is echo only for my correspondents.

I have downloaded the latest version Free version. Still the same problem.

What do I do ? 

Thank you 
David

Comments

If the issue appeared suddenly, without you updating Zoiper or your system, try contacting your VoIP service provider and let them know of this issue. They may have some issue with their lines.