Wednesday, October 12, 2011

Cisco Wireless VoIP 802.11n phone?

Cisco announced a few days ago the end of life / end of sale for their Cisco Unified Wireless IP phone 7921 (see here). The 7925 is the last end user product in the wireless line (even the CB21Ag card, with its PCMCIA format and lack for Win7 support is dying away)... so will Cisco give up and soon throw away the 7925 as well, or will they come up with new product and a 802.11n phone?
Cisco is clearly moving away from the end-user market, but WiFi phones are an enterprise product that complement the large range of Cisco wired IP phone.
But a 802.11n phone? Cisco has already certified the Cius as a 802.11n phone. Cisco and Dell are the only ones having a Wi-Fi-only 802.11n phone (see here), but there are hundreds of dual band GSM/WiFi certified 802.11n phones (see here).
All these phones are single radio, single stream. This is allowed by the 802.11n amendment, and is expected to last for a while. The main concern in a phone is to conserve battery. As soon as you put 2 radio modules in a device, you consume twice as much power as another device with a single radio module. Although you can find clever ways to use the second module sparingly, your phone battery is still going to last a lot less than you competitor's single-radio/single stream phone... not to mention the technical challenge to put 2 or 3 radio modules, with 2, 3 or 4 antennas, in a device that has to be light and fit in your hand.
Isn't single radio/single stream enough anyway? If you use your phone for what it is... a phone, you need to send a receive 50 packets per second, consuming about 200 Kbps. So why bother with 802.11n? The gain in range might be useful to you, but all design guides work hard at convincing wireless network designers that they should design small cells, to control the data rate and number of devices in their network. So you might be able to take advantage of the additional range provided by 802.11n, but only if the network you join is poorly designed... :-D
Most dual band phones certified for 802.11n offer this certification to allow for a more comfortable browsing (and downloading) experience, not really for the voice part itself.
So it would probably make sense for Cisco to work on 802.11n hybrid devices (phone + something else that needs bandwidth, like the Cius and its telepresence feature), but probably not for a pure "phone only" device... I have no internal insight on Cisco secret plans, so this is just a thoughts I figured I should share, as I often get this Cisco 802.11n phone question, but this is by no means an informed or even educated guess on Cisco strategy... :-)


  1. Most access points only support a single mode per SSID so if a g device like a phone where to connect in a single SSID environment it is now lowering the bandwidth options for other devices on that access-point. That to me should be the biggest reason. Even in an enterprise environment managing multiple SSID's is a pain. I suppose based on best practice multiple SSID's is the preferred option to segregate the voice and give more control over QoS....

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