Q: When i call someone, the other person hears echo of his own voice.This happens all the time in all locations.Any help please??

When i call someone, the other person hears echo of his own voice.This happens all the time in all locations.

I am using STC network in Saudi arabia.(KSA) but i have also tried this using other networks in KSA and also with networks in INDIA.

Any help would be highly appreciated. ??