IP addresses are familiar sights on the Internet. They're the sequence of four numbers separated by dots, such as They uniquely identify a device to the rest of the Internet. There's just one problem: Using the traditional scheme known as IPv4, there aren't enough IP addresses to go around. Each of the numbers is in the range of 0 to 255, making up a 32-bit address. This gives 4,294,967,296 possible addresses. It's actually a little less than that, since the protocol reserves some of those numbers for special purposes. Every device, including VoIP phones, needs its own address.

Tricks of the Trade

Four billion addresses may sound like a lot, but it's not enough. It's not that the Internet is going to run out of addresses; it has run out, and networks have to play various tricks to give all their devices addresses. The main trick is Network Address Translation (NAT), which lets a lot of devices share a single IP address on the Internet, while each one has its own address on the local network.

The Disadvantages of NAT

The NAT approach causes problems, since a NAT device needs to juggle addresses. For simple things like connecting to a web server, it's not too bad. If a computer has to change addresses in the middle of an HTTP session, that usually doesn't cause problems. But for sessions that require a continuous connection and multiple protocols working together, the problem can be more serious. VoIP sessions are an example. Glitches due to NAT issues can result in the loss of audio on one or both sides.

Leave It to the Experts

There are ways to work around the problem. One is to give each phone its own public IP address, but that can be difficult. Even with NAT, it's possible to configure the network for reliable connections, but it takes considerable expertise. It's not a do-it-yourself job, even for people who understand ordinary computer networks but not the intricacies of VoIP.

The second part of this blog will explain how transitioning to IPv6 is the best way to solve the problem of limited IP addresses.

For information about how TelWare can aid your transition to VoIP or improve your existing network, simply contact TelWare at 1-800-637-3148 or sales@telware.com. TelWare is a national leader in the installation of voice, video, data and unified communication solutions. TelWare is an authorized Avaya, Star2Star and SimpleWAN dealer.

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