In our setup, we have a mixture of phones that are permanently powered (VVX 150, and Yealink W70B), and some that get powered down overnight (All VVX 150). The phones that get power cycled will often not register properly (at least I think that's what happening) and give a permanent busy tone. Is there any way of looking at the phones logs to see what they are upset about?
The best team to discuss this with would be our BT Cloud Phone support team on 08003890598.
If you message me directly I can take your business details and arrange for them to contact you.