cisco wireless ip phone 8821 "network busy" fix

[Abdull_Cisco]

Dears,

For your kind support as I am facing an issue in cisco wireless IP phone 8821. The issue is that the cisco wireless phone always gives network busy when making a new outgoing calls as well as receiving calls it goes to a busy network immediately once receiving a new call...

The Phone is registered perfectly with no issue to the CUCM 12.5.

Your Advise Please 

[jeremyseielstad]

I had the same, or at least a very similar experience with our 8821's.  The phones would get on the network and show as registered in CUCM, however when there was a call to or from the 8821 phone (running either firmware Active Load ID: sip8821.11-0-6SR5-5 or Inactive Load ID: sip8821.11-0-6SR2-4) they would experience a network busy error.  We tracked it down to a specific access point in our network.  Any time the phones were associated to this one specific ap (Cisco C9136I-B Software Version17.9.5.47 ) the issue would occur but when they would roam away from it the phones worked as expected. There were no issues showing on the controller or in DNAC.   In the end we rebooted the AP and the issue was corrected.