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VoIP & Wireless


I really need a sanity check and was hoping someone here might be willing to share their experience and possibly any good articles/documentation they know of.

I am in charge of a relatively large wireless deployment in my building, probably somewhere around 50 to 60 WAP's (Aironet 1200's, 802.11g) and the idea has been repeatedly thrown out there that we could use this wireless network with wireless phones and VoIP. Yes, I know that there are phones out there that can associate with Aironet WAP's and all that. This isn't a question of technical abilities..yes, it is possible. But..the real question is whether or not it is ready for primetime yet.

For Example: Using a Wirless VoIP phone is it feasible to expect to be able to roam across multiple WAP's while you walk and still have a quality phone conversation? What if a person was going between floors and stepped into an elevator? Has anyone see this sort of thing actually work? My managers are convinced that this is going to be great, but I am very skeptical that the technology is ready for this kind of application.

Can anyone please offer their thoughts? Perhaps Cisco has some best practice documentation that would show what they consider to be real world deployment scenarios that work?

I am happy to rate you very highly if you can offer me some of this info, I really have reservations about the scalibility and voice quality of conversations in the scenarios I mentioned above. Especially in a higher security environment.


Re: VoIP & Wireless

We are using 7920s in a building with 4 floors and 10 1200 series APs and have had great success. Take a look at the following link. It addresses some of your concerns about roaming, etc. The elevator example would require that you have wireless coverage that extends to the elevators.

Is Your WLAN Ready for Voice?

Hope this helps.


Re: VoIP & Wireless


Also do take a look at various WLAN requirements before deploying 7920s in this link.

a. Especially the cell size has to be - 67dbm.

b. Separation between same channel cells - 19dbm

c. cell size shouldnt be too large, as each ap should handle not more than 7 or 8 calls (g711, g729).

d. Installing APs to cover elevators can be a challenge, as elevator walls are firewalls.

e. Disable 1mbps speeds as they use long preamble.


PS: please remember to rate posts!

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