Calls to analog ports not releasing

[busster]

Hotel customer with G3siV12 is having strange issues with calls to analog phones not releasing. This has just recently started happening. If an administrative person from a digital phone, attendant console or other display phone, calls a guest room, sometimes they can not release the call. This is also happening to analog voicemail ports. If an administrative person calls someone who does not answer and the call is answered by voicemail, the voicemail continues to record even after the calling person thinks the call is hung up.

I see no alarms or errors in the system relating to the issue.