Cisco 8821 wriless phone not registering with CUCM

[Jahangir Tahirov]

Hello, cisco 8821 wireless phone not registering with the CUCM.

When powering off and then bring it back it works (registering ) sometimes but not all times that kind of restarting helps.

When changing to connect another SSID and the connecting back former SSID it works.

ALL of these attempts not fixing the registering problem after 1 or 2 days or 1-2 hours it beeing unregister.

CUCM  System version: 12.5.1.10000-22

Can anyone encounter this kind of problem?

[Leo Laohoo]

What firmware is the phone running on?

[Jahangir Tahirov]

Firmware version is sip8821.11-0-4sr2-15

[Leo Laohoo]

How many phones are affected by this?

[Jahangir Tahirov]

we have only one wireless phone and only that phone connected access point .

[Jahangir Tahirov]

I am trying to look logs from 8821 but only it shows only logs when it was registered state. After losing registration it won`t show logs . 

[Leo Laohoo]

I'm trying to determine if this is a CUCM issue or a wireless issue.
So when this issue occurs, is the phone joined to the wireless or not.

[Jahangir Tahirov]

The phone just getting unregistered after reboot or some time. Time is not the same all-time for ex one time it gets 1 day after, another time it gets 10 days later and sometimes it gets 1 hour.
IT still connected wireless network but get unregistered state. we check thought ICMP to phone responding.

[Leo Laohoo]

OK, so the phone is still connected to WiFi when this issue occurs.
Have you checked the phone and CUCM logs and see if there are anything unusual?

What QoS is the SSID the phone is connected to?

[Jahangir Tahirov]

When the phone got an unregistered state I can`t log into the phone to saw logs.
we don`t use a wireless connection in our environment but only we bought an Ap for only cisco 8821.

So that Ap has a very basic setting not have a QoS setting.

[Jahangir Tahirov · Accepted solution]

After changing wifi ap from 2.4 GHz to 5ghz  problem has been solved.

[user64595]

Same issue with sip8821.11-0-6SR5-5.  

Configuring my basic AP like this : "Voice QoS", 5GHz, beacon 1, dtime 2, proxy  ARP and removing 802.11k .  It is much more better.