I am using 9611 phones and when the user is on an active call the other end will suddenly hear music as if the user put them on hold. The music will play for a few seconds, then reconnect without the user ever placing the caller on hold. This is happening to several phones but I've never heard of this before. I show no alarms and no errors in the PBX, and the network guys say everything looks good on their end. Anyone ever run into this???