I don't know if this has been posted since the search feature does not work very well, but we had a problem where the speaker in the base of the 5330 stopped working. We have about 400 of them that we have purchased over the past 2 years and the speaker died in about 6 units. We probably got a bad batch. Anyway, after our dealer said that nothing could be done, we opened them up and found that the wires to the speakers had not been soldered on, so they had come loose and fallen off. I have no idea if Mitel knows about the problem. We chose to just solder them on ourselves which was a quick and easy fix. Certainly easier than sending them back.