What would cause 2 DKT to stop following System Call forward settings?

CIX670 System CF 1 set to Busy and No answer Active destination is voicemail (4000)

Ext 3097 and 3292 have just stopped forwarding to voicemail. Both of these are programmed the same as 3212 which is working without issue.

For temp I had the client forward from the phone #6041 4000 20 to get the mailbox to answer

Intercom #621?
The same code the DK used to change display name. It used to happen all the time when customers were upgraded from the DK platform.

So #621 is a system call forward over ride? The client swears they did nothing and it just happened.

Have them try Intercom #620 to activate system call forward anyway.

It always just happens for no reason other then the PBX has a mind of it's own.

On a 3rd trip to one location I removed #621 from the system.