BCM 50 Rel 6 incoming calls can only be answered by ext 221

[TnPhoneguy]

BCM 50 rel 6 an incoming call flashes and rings on ext 221 all other phones have a solid arrow. This is happening on line 3 this time 2 weeks ago it was line 1. It almost acts as though the call is being transferred to ext 221. Last time I rebooted the system and it cleared the problem. They do have voice mail activated at night with auto attend.
Thanks

 

[cook1082]

Check the lines for disconnect supervision. Patch?

 

[TnPhoneguy]

The system is about 2 years old and that was the last time patches were applied.