I have a few hotels setup with IP 406 and 412 system. They are using the Duvoice voicemail system. On occasion they get an issue where one phone locks up its call appearance. You have the phone icon on that appearance like there is a call there and it never goes away. Also when a call rings the huntgroup that phone wont ring. You answer the call on another extension and when you hang up, the phone with the stuck line will start ringing. This only happens on front desk phones. Any one else experiencing something like this??