The issue: during incoming calls there is a loud ring tone through the speakers but when pressing "accept" (Main for less than a second) I cannot hear the caller and the caller cannot hear me. The display shows an active call (call1). The display does show a cross through a speaker (mute?) but pressing that button does nothing - but I do hear the ring tone?? I've looked through the manual and there is no advice in the problem chapter.

Can anyone help?

Its similar for outgoing calls. I can get Blue&me to make the call but no one can hear me... aghhh!!!