something you can try.
1) make sure the carrier have the hardware you're using is registered to you and not your old phone.
2) use a headset w/ mic and make a call to see if there's an echo.
-if this is yes, it could be your carrier tower OR your hardware
- if no, then it's your hardware.
3) use a speaker phone and see if there's an echo.
-if this is yes, it could be your carrier tower OR your hardware
- if no, then it's your hardware.
if the problem still keep up, or been fixed, let us know! ^_^