No ideas ? Can not call Toshiba as cards are from a local telebroker. Boss had checked cards at the broker to see if they had enough licensing but he did not test card. Broker says they tested the cards. Have not experienced this loud volume from a phone before. Boss says it is loud volume but to me it sounds like a real loud buzz when you go off hook. Can not find any similar problem like this from searching the web. Guess I will have to take the cards back and have them put them in a 670 and test them.