5xi Problem with BLF and DND/Call-forward

Any time, when a phone have DND or Call Forward activated, and there is a call on this phone (call is ok: busy if dnd, forwarded if call forward), other phones that have this phone in BLF/supervision see his LED blinking during 3-4 minutes.
During the problem, when blf led blinking, the hint of phone is "idle" in asterisk (it is good, there is no call on the phone)
In this case, three solutions:
- blf led stop blinking if I desactivate the DND of the phone
- wait 3-4 minutes
- reboot the phones who have the dnd phone in blf supervision

Any idea ?

thanks