voip

Quite a topic to cover. Perhaps you'd be best to get onto Cisco's site

http://www.cisco.com/warp/public/779/largeent/design/multiservice.html

and look at what they have to offer. Also, 3com is coming on strong with Voip equipment solutions.
Essentially, a question like that is way to complex for a forum like this. 1930 characters would just about suffice to define voice over IP, but to explain it....

The key to VoIP is BANDWIDTH, and some very healthy routers and switches. You will need at a minimum a Cisco 2600 at remote sites, and a Cisco 3600 series at the central site.
Full T-1 is the minimum connection, with ATM recommended.

All the above will enhance your existing LAN, WAN, and give you capability for VoIP.

Next, you have to buy and implement the ancillary equipment, basically, boxes to replace your existing PBX's, IP telephones, and Special Patch Panels to provide 48vdc to the line. One consideration is that you should NOT use existing Cat-5, as you arenow applying voltages, which will affect your data connections, so new cabling, new pathways are called for.

Next, you will need the management modules and software to set-up, configure, and control the voice traffic.

Last but not least, unless you only want an internal ( to your WAN ) phone system, your Telco provider must be able to connect your VoIP network to their switching equipment.

any help?

I think the first answer is making it more complicated than it needs to to be. The only way in which VOIP is different than normal data traffic is that timing is crucial because the packets must arrive on time and in order. As a general rule, a T-1 is recommended but I've worked with successful implementations using 56k frame relay. Bandwidth is not nearly as critical as latency and other forms of delay. The system with which I currently work uses about 16k of bandwidth for background tasksand about 10k per conversation so the peak utilitization of the T-1 rarely rises above 60-75k.

The general procedure would be to select a vendor for your VOIP-specific equipment and then use their specs to evaluate your network infrastructure. In some cases, that may mean changing out routers (in our case, we went from Cisco 2501 to Cisco 3640) or upgrading router software. You'll also want to take a look at your subnetting scheme and make sure you have enough IP addresses available for all the desksets.

For the VOIP-specific equipment, it will depend on what else you have going. At the very least, you'll need desksets and a switch to interface to the public telephone network.

Some VOIP systems can be pretty close to plug-n-play if your network is up to snuff and you're willing to accept some deterioration of voice quality. To really do the job right, you'll need to set up your network to give priority to the voice packets.

Hope this gives you a start!

paul