I recently had a Partner ACS module fail. It was used with 206E, 308EC, and VMS modules. All settings were lost since it was never set to make monthly backups. It has since been replaced and configured. Everything seems to work better than ever (we even have caller ID with number and name now), but we are hearing a faint sound over the PA system that sounds like a phone is off its hook. It is loud enough to be annoying when things are quiet. We do not use every extension, but the extensions that are in service do not have phones off their hooks. What could be the problem?