A12 callers can't hear me

[HELPSomeonePLEASE]

A12 callers can't hear me.  Brand new phone.  Replaced a month later with same phone.  EE and Samsung contacted did all the tests and factory restart.  Still happening.   HELP PLEASE

[UFH]

I had the same problem. When I turn on speaker phone on incoming and outgoing phone calls I am heard. Thank goodness. 

[Ercatli]

Similar problem. Phone has worked well for several years, but just now whoever I call or call me can only hear faintly. Using speakerphone works OK, so it can't be the microphone can it? Must be the software.

So hoiw do I fix it please?