Polycom without microphone

Hi guys, here we use Polycons phone to make and receive our calls.
Friday the microphone of one of those stopped working on calls, if I test the hardware it records and reproduces my voice. But when I call someone they can’t hear me, but I can hear them.
I don’t know if this is some kind of configuration, or if the phone is dead.
Can you help me?
The model of the phone is a Polycom IP330 SoundPoint