Phone rings but when answered the caller can not be...

The phone rings but when answered I can't hear the caller & the caller can't hear me. The same happens when I dial out. I can't hear the phone I'm calling ringing & if answered I can't hear them talk.
In short there seems to be no audio when using the phone.
When I use the touchpad it still makes the tone noises & it rings & does alerts etc. so it doesn't seem to be the speaker, it is only the audio for phone calls.
I have tried all the settings, volume, conectivity & everything else I could think of.
Anyone got any suggestions?