When Erlanger Health System chose Nortel Networks to provide its IP telephony hardware and software, Nortel's first performed a full network audit. The inspection revealed how little the IT staff understood about impending network requirements, says John Haltom, network director at Erlanger.

The audit "was shocking proof of how much we needed to get a better understanding of our network prior to going large-scale with VOIP," Haltom says. For example, networking gear that could handle data traffic with only minor delays would not be capable of handling the stress of voice data, he adds. "We had duplex mismatches, NIC cards chattering in several locations -- all of which have some minor effects on data-based traffic," but with voice they would be a menace.

Of course, audits are a prelude for vendors to sell products, and they "aren't always looking out for your best interest," cautions IDC's Stofega. With that in mind, internal expertise, in addition to conferring with consultants and outside colleagues, become invaluable.

Ensuring that users get the voice services they need also hinges on cabling, according to Joanne Korsuth, CIO at Olin College of Engineering. Cabling will determine the viability of future services. With an eye toward expansion, you'll want to consider stackable switches with 24 or 48 ports each.

Power is also a consideration, Korsuth says, "so we have UPSes [uninterruptible power supplies]. That seems like common sense, but with VOIP, wireless, and power over Ethernet, it's as important a consideration as cooling in closets."