Voice Over Wifi Issue: random service interruption

[nizar.houichi]

Hello,

I have implemented a Voice over Wifi solution based on WLC 4404, AIR-LAP 1131G and CP-7921G. The Security mode deployed is WPA PSK. I have a random interruption on wireless access witch cause the CP 7921G to lose connectivity to the CUCM, even if the Phone is near to the AP and does not move. What can be the cause of the problem. Thank you in advance.

Best Regards

Houichi Nizar

[choiwon]

sounds like there can be an RF issue causing the service interruption. is Auto RF enabled, any messages on the WLC? has there been a site survey done? what is the firmware version on the phone? is the phone registered to the CUCM / CME?

we'll need to find out where the issue is first and we can drill down further

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[robvreede]

Hi,

we are experiencing the same issues.

The VoWifi design guides (i.e. TPC, DCA, Media, EDCA, WMM, QoS) have been followed setting up the Controllers.

Tested WLC4402 / WLC4404 with firmware versions 4.2.207 and 7.0.116.

Experiencing the issues on 7921G (firmware 1.3.4SR1) and 7925G phones (firmware 1.3.4SR2 and 1.4.1SR1).

The access points used are 1242G with a mix of AIR-ANT1728 and AIR-ANT24020V-R diversity antennas.

It is a warehouse environment. Phones are very near to access points.

We only use 802.11b/g for wireless phones and data clients.

The only issue I found is the cell size which is small and AP transmit power is low.

Auto RF and Auto DCA is enabled. AP power levels are 5, 6 or even 7 in areas with a lot of access points.

We have a high density b/g clients on some areas in the warehouse and added some access points to seperate the AP load.

Kind regards,

Rob Vreede.

[robvreede]

Hi,

going back to version v1.3.3 was the solution for us.

The new inter band roaming algorithm might be causing the Voice issues.

We do not use the 802.11a radios (available, but disabled).

Even configuring b/g on the 792x phone did not stop it from scanning the 802.11a band.

Reference: http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7925g/firmware/1_3_4/english/release/notes/792x_134.html#wp240885

Kind Regards,

Rob Vreede.

[migilles]

1.4(2) will have more aggressive scanning.

If 1.3(3) works better than 1.3(4) or 1.4(1), then open a TAC case and may be able to provide some dev phone code.

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