VOIP on WLAN

[maverick9]

hello guys,

We are planning to implement VOIP in our company. We have wireless as well as wired network. We are also planning to replace the existing phone network by VOIP. I would like to know what all areas do i need to consider for VOIP on WLAN.

thanks in advance

[spiderbite]

Oh my goodness, where to begin.

First, I would like to ask why you plan on replacing the POTS with VoIP as opposed to enhancing it?

Second, you need to decide on how many users you will have, then figure out how many users will be on the network actually making a call,
during slow, normal, and, busy times.

These figures should help estimate how much throughput you will require for your WLAN.

Incidentally, do you also plan to run data over the WLAN?

This must be factored in as well.

So once you have determined how many users will be using how much throughput in several given scenarios,

then you should determine just exactly where you want this service to work.

Once you have that figured out you can estimate the number of AP's required to give you the throughput you require / want.

Keep in mind that you must plan for growth etc...

Then you need to do an exhaustive site survey, to determine exactly how the building is going to interfere with your goals. Preferably using an actual "voice" as opposed to

guessing with airmagnet etc...

Once the survey is completed, a compromise between what you wanted and what you can have must be reached.

Then you need to see whether or not your current backbone infrastucture can support the Vlans, QoS, power over Ethernet, etc..that will be required to do voice.

Then you need to see if you have any money left over from the proposed budget to the "updated" budget.


I could go on...

[M/Q]

Great post Spider. To be sure.

[ibartolic]

It is true what Spider is talking about.
But you have applications like Net Ally (I worked with that one), that are testing readiness of your IP network for VoIP traffic.
First you install agents on crucial places in your network and generate calls. (You have to define number of calls between agents and choose codec). Then you have statistics about parameters crucial for VoIP (dropped packets, delay, jitter, MOS) and check do they have reasonable values.
With that you know is your network good enough or do you have to improve it.

Igor

edit by admin: no commercial links permitted on the forum, thank you

[yogesh sehgal]

How many concurrent Wifi phone can be register per AP on 802.11g on 711 codec.
How many concurrent wifi end point can speak with each other at any point in time on the above conditions
Does D-link AP or I have go for Cisco's AP, what is the difference bewteen the two in terms of Range and concurrent login/concurrent speech path..

[John_in_NC]

You wont be using DLINK, you will probably go with lightweight cisco with 4402 controller so when you walk from one AP to another (roam) your login credentials will fast switch to the other AP (<100ms) otherwise your users will go crazy with the dropouts.

I set these type of networks up for my day job. You are looking at a totally different league of equipment that carries a much heavier price tag. But if you can get management to realize the benefits (which are huge) it will be well worth the trouble.
Even if you could set it all up, I would suggest you go with a vendor that does this all the time to set it up for you. Setting this up this type of equipment and getting it right requires, tools skills, and vendor access that exceeds that of a typical sys admin person.

Beside, it's better off having someone else take the heat if it does not get set up right!