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10 things you need to know about VoIP

Before rolling out voice over IP in a business, it pays to tap into the lessons others have learned.

By and Phil Hochmuth, Network World
January 29, 2007 12:06 AM ET

Network World - Anybody working on a VoIP project should stand on the shoulders of those who have gone before to avoid their mistakes and glean tips that can make their own deployments go more smoothly.

In the interest of promoting this knowledge sharing, here is a list of 10 tips you should follow if you want to roll out VoIP with as little pain as possible.

1. Buy time.

Even with the smoothest deployments, things don’t always happen as planned, so build a buffer into your timeline, says Lauren Johansson, IP telephony manager for MedQuist, a medical records firm in Mt. Laurel, N.J. For example, in Johansson’s case, getting an OC-3 from her carrier took an extra six months during which MedQuist had to make do with a DS-3, a lot less bandwidth than it wanted.

2. Get everybody onboard.

Make sure business-unit leaders are on the VoIP project team so they know the details and can communicate them to their employees, giving all users a stake in the project. “This reduced switchover time and made for little need for user training,” says Randy Hillman, customer care manager for Sovran Self Storage, headquartered in Buffalo, N.Y., who oversaw a Shoretel VoIP deployment.

3. Know what you’ve got.

Along with traffic, businesses need to figure out exactly what hardware makes up the network infrastructure and more important, whether it will support technology that can improve voice quality. For instance routers and switches that support virtual LANs and traffic shaping go a long way toward carving out enough reliable bandwidth to prevent degradation of VoIP connections. “If you don’t have an accurate network diagram, you can’t do a project like this,” Johansson says.

Also, make sure all desktop deployments pass the PAS test. That is, desktop phones should have two things — power and switching (PAS). Make sure phones can be powered via standard Power over Ethernet (PoE, 802.3af is the IEEE standard). Also ensure that the IP phones being deployed have built-in LAN switch ports. This will allow for a single LAN cable to support a desktop PC and IP phone (the PC connects to a LAN port in the switch, which uplinks to the LAN). And if users require Gigabit Ethernet, make sure the IP phone has a 1000Mbps port.

4. Bandwidth control.

If audits reveal that bandwidth may be an issue, it could be time to consider an upgrade from, say, Fast Ethernet to gigabit Ethernet. Even if such an upgrade seems like overkill now, it makes sense to project network traffic increases from all applications over the next three years to determine if such an upgrade is inevitable.

LAN bandwidth turned out to be sufficient when Sovran Self Storage decided to install Shoretel VoIP gear to 330 sites, but the ATM WAN needed a bandwidth boost, says Randy Hillman, the firm’s customer care manager who oversaw the VoIP project. That turned out to be a combination DSL and cable modem network backhauled over an MPLS service and coordinated by Verizon, he says. “That lets us give priority to voice,” he says.

5. Use the right codec.

To minimize bandwidth that VoIP requires, customers can choose from a variety of codecs that take the voice stream and encode it for transmission over network wires. This can be as little as 8Kbps or as much as 64Kbps, but businesses should listen to a variety of them to determine which ones produce acceptable quality. The ones that are acceptable and use the least bandwidth are the ones to use, especially if bandwidth is tight.

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