Solved: is 802.11a better for Wireless IP phones?

Eric.Wang · ‎05-15-2009

We have 7920 phones running at 802.11G but users complained about choppy voice and interference. I can not explain why but it can be from nearby RF noise...

Now we're getting 7925G phones to replace 7920.

Is it a good idea to configure phones to operate at 802.11a instead of 802.11G?

* Pros of 802.11a - fast maximum speed; regulated frequencies prevent signal interference from other devices

* Cons of 802.11a - highest cost; shorter range signal that is more easily obstructed

Has anyone done this? or it's not a smart idea?

migilles · ‎05-16-2009

5 GHz is always recommended. Sure you may need more APs, but you have more channels and less interferers. For the 7920 having issues, it could be due to interferers in the 2.4 GHz band. If you have the Cisco Spectrum Expert software you could check for interferers. Also you can simply look at the CU value in the 7920 site survey, which will show channel utilization. You need to enable dot11 phone dot11e to see this value. If this reaches 100, then the channel is getting quite busy and can then start to see packet loss. If 802.11 traffic is not the cause, check for interferers.

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migilles · ‎05-16-2009

5 GHz is always recommended. Sure you may need more APs, but you have more channels and less interferers. For the 7920 having issues, it could be due to interferers in the 2.4 GHz band. If you have the Cisco Spectrum Expert software you could check for interferers. Also you can simply look at the CU value in the 7920 site survey, which will show channel utilization. You need to enable dot11 phone dot11e to see this value. If this reaches 100, then the channel is getting quite busy and can then start to see packet loss. If 802.11 traffic is not the cause, check for interferers.