Customer has a UC560 with 7942s, 7962s, and 7975s phones. IP phone to IP phone quality is fine. Calls to the PSTN are hit and miss. Some calls are fine and other calls are not. Customer is complaining of hollowed sounds. One of their customers told them that they sound like they are in a water tower.
Anyone have any idea what we can do to improve the quality?
I have changed from G711ulaw to G711alaw and no difference in quality.