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Sergey Balyura

7921s are disconnecting


I have the next trouble. I have CUCM 7.1.(5), WLC 5508 and bunch of 7921s, 7911s

And I have a lot of disconnects. often a conversation with 7921 (every one of a bunch) is lost.

I have the last firmware on 5508 - I have H-REAP

And I loaded the last firmware for 7921...

Can you help me in resolving?

Sergey Balyura


Hello again!

We have not done site survey yet... but I saw the disconnection of 7921 which was just under 1242 AP. And I heard a silence. there was no signal of busy or anything else. Just the silence.

I'm not sure it is a wireless trouble.

And now I have another very sad problem. My WiFi network become very strange. every Wifi device cannot recieve any resource: notebok or IPhone cannot connect to intranet or internet point,7921 cannot register. I cannot find out the reason. But once I could heal it by rebooting of 5508. once I had to reboot 5508 with all myAPs.

Can you help me how I can investigate the reason of such kind of problem?


     I meet the problem same with you . I want to know have you find the reason at last? thank you

I have same issue "Leaving service Area"

anyone have solution for this. WLC 7.4,  AP-1602,  7925Phone.



in my situation the reason was that I have more DHCP clients then DHCP scope. I enlarged the DHCP pool - it fixed this trouble


thank you for reply.

DHCP pool are free almost with /24. This isn't my issue.

can you please advise anything else?

I have experienced that with the correct configuration, things didn´t start to work correctly until those phones 7921 and 7925 are downgraded to firmware version 1.3.4 latest service release. It is still like this years later that the most recent firmware simply doesn´t work for basic thing such as roaming and FSR roaming, even though the phone , wireless and everything is Cisco and correctly configured. I have only seen one case out of 5 that I can remember that the WLC upgrade fixed issues like that.



Please check latest release updates of IP phone, AP and WLC 5508
and configure noise free channel on APs.

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