VoIP: Stack the deck to win or lose


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If you're in the Fortune 1000 and your firm doesn't have a VoIP (voice over IP) pilot project currently in the works, you're already behind the times. When upper management demands to know what you're doing about "this IP telephony thing," what are you going say?

Say, "All I need is $80,000 and six months, and we'll be ready to roll."

Now, you might actually be able to get by with $50,000. And I've seen a few VoIP pilots get off the ground in just three or four months. But it never hurts to build in a little buffer.

Once you've bought the time, you can decide whether you want your pilot program to succeed.

Go out and get two low-end VoIP gateways. If you want to go with the market leaders, there's Cisco's AS5300/Voice Gateway or Lucent's MultiVoice for the Max 6000. But what kind of network do you connect them over?

Here's where you can stack the deck. If you don't want to be bothered with VoIP any more, connect two of your corporate VoIP sites over the Internet -- via two different ISPs, if you can arrange it.

Here's what will happen: Between 30 to 70 percent of the time, realtime phone calls will work just fine. But the rest of the time, latency and jitter will drive your pilot testers nuts.

But let's say you want your VoIP pilot to really sing. Then connect your two VoIP pilot sites over your own intranet (that's your private backbone data network). This assumes your private IP backbone is well-managed and behaved; I've seen a few that are worse basket cases than the Internet itself.

VoIP gear will add about 80 to 90 milliseconds of one-way latency. If you make sure the network consistently adds no more than about 30 to 40 milliseconds (that's like cross-country propagation with a few high-speed router hops), and keep total one-way, end-to-end latency consistently under about 120 milliseconds, your VoIP users will be impressed with call quality, and your management will be impressed with you.

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