I have a problem on a customer site that uses an officeserv 7200 with a 5021D handset.

People who call that extension (5021D) cannot hear the user on the phone. I thought that maybe the phone has reverted to headset mode and told them via phone to revert mode and the problem was solved for a while. I also made sure that the phone is on ring mode and no call forwarding or DND is configured.

The problem is that it changes again state to headset mode somehow... . One more thing is that there was an older model 21 button key programmed phone before we put the new 5021d phone. This is the only 5021d we are using before installing another three. unfortunately at the time being I don't have spare 5021d phones to see if the problem is the phone itself.

Has anyone come across a situation like this?
When in handset mode and the user presses the send button or end button does it revert to headset mode?