Cisco CP 8821 Call drops and audio issues on a stable Wi-Fi

[h.matsalia]

Hi, 

We are having troubles deploying Cisco CP 8821 wireless phones. In our test environment, we have configured wireless profile for one SSID and one wireless profile group, which we have added to the phone profile for the CP 8821. The phones are well registered on the CUCM and they have picked the SSID defined in the wireless profile. But the wireless phones can't call each other, the call keeps dropping but when you call the deskphone the call goes through but the voice is one way. The one on wireless can't hear the one on deskphone but the one on deskphone can hear the one on wireless. The wireless can call the deskphone but when the deskphone calls the wireless the call also drops.

CUCM 14, Deskphone CP 7821, All the phones (SIP) running the latest firmware. 

If someone can advise on how I can reslove this I will really appreciate.

[Flavio Miranda]

@h.matsalia 

  I would set “Call Power Save Mode” to none if you have it set to “U-APSD/PS-Poll”

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/8821/english/adminguide/w88x_b_wireless-8821-8821ex-admin-guide/w88x_b_wireless-8821-8821ex-admin-guide_chapter_00.html

[h.matsalia]

@Flavio Miranda 

Thanks for your input, we are using D-Link Access Point, DIR-880L. Transmission power was set to high. I've tried to turn it to low but the issue still there.

[Flavio Miranda]

The config I suggest is on the phone 8821. You can check the link I shared.

Transmission power set to high is not necessary a good thing. You need to site survey the local and check if the coverage is fine for voice. Too much signal can be as bad as weak signal.

[h.matsalia]

Thanks for your response @Flavio Miranda ,

It is possible to do it on the phone itself, but when you apply the wireless profile in the cucm for the phones the "On Call Power Save", comes automatically Enabled and we are setting Disallowed modification so that once connected users should not change wireless settings. With those configurations we won't change Call Power.

[Flavio Miranda]

I got the procedural part but you are in a troubleshooting scenario now.  Did you try to disable the power save in one phone at least and test?

[h.matsalia]

Yes.. I tried to disable the Power Save, calls still dropping no audio in the wireless phones still

[Flavio Miranda]

I dont know this access point but as per the documentation it seems it supports firewall. For the next steps I would take a close look on this AP config. One way audio could be firewall blocking RTSP or even NAT. This could also explain calls drops.

https://media.dlink.eu/support/products/dir/dir-880l/documentation/dir-880l_a1_manual_v1-02_eu.pdf

[h.matsalia]

Thank you @Flavio Miranda ,

Is a firewall AP but no any firewall policy is enabled. The RTSP was enabled, I turned it off but still there is the issue of calls dropping the moment any of the wireless is called and no voice for the wireless. No NAT, on LAN we have DHCP 192.168.2.0, and on Wi-Fi we have DHCP 192.168.0.0. Every phone is registered on the CUCM with it's own IP address, 192.168.0.XX for CP 8821 and 192.168.2.XX for Desk-phones.

[Flavio Miranda]

Can you run wireshark somewhere in the flow and share the .pcap file with us? Not sure how your topology looks like, but it could be done on the switch where the AP is connected.

[Leo Laohoo]

What firmware is the 8821 running on?

[h.matsalia]

Hi @Leo Laohoo ,

Standard SIP 8821; sip8821.11-0-6-7

[Leo Laohoo]

That's 11.0(6)SR0.  That's a "version ZERO" firmware. 

Update to 11.0(6)SR4 (or later) and try again.

[h.matsalia]

Hi @Leo Laohoo ,

The phone was running sip8821.11-0-6-7 firmware, I uploaded a another firmware sip8821.11-0-6SR5-5 (SR5), but it does not resolve the issue. Still having same issue.

[Leo Laohoo]

Is the issue happening when the handset is roaming or standing still?