T38G not Hearing the voice

[supportimtlucca]

Hi, we have since a couple of days a problem with our T38G.
When I call someone from the phone the receiver can hear me but I don't hear him.
I need to try a couple of time to call and to switch from loudspeacker to normal one and in reverse to can hear the receiver.
After it works I can make calls and it works normally.

The problem arise again when I don't use the phone for some time.

I upgraded to the last firmware version as well to try to resolv the issue, but it's the same.

Any help?

Thanks