Even companies with considerable experience with VoIP move cautiously into this new terrain. Halliburton Energy Services, the Houston energy giant, has been experimenting with WAN-based VoIP since 1996. (Currently about 15 percent of the company’s more than 100 sites can place calls over the Halliburton WAN; there would be more, but VoIP is restricted by law in many of the countries where Halliburton operates.) In late 2000, Andy Knight, who is responsible for Halliburton’s network communications (his actual title is Chief Gadget Guy), decided to begin moving to IP telephony. His first step was to install an experimental system that ran in parallel with a conventional PBX and carried calls only among members of a single office (with no PSTN gateway). He used this system to support experiments with features and build bandwidth utilization models.

By late 2001, Knight had gained enough experience to move the technology into a production setting. Once again, he picked the site that would deliver the most education for the least risk, specifically Landmark Graphics’ (a wholly owned Halliburton subsidiary) London office, which was then moving into a new building. "We had all the business groups there but in a smaller package than in Houston," Knight says. (The London installation came to about 150 phones.) Like Amerine, he found that VoIP networks are picky about where they choose to work. "Laying a cable over a light might not affect performance in a conventional network, but even low levels of electrical interference can be a problem for voice," he says. Knight also agrees with Amerine that companies need to have their own expertise on the technology: "VoIP is still too new to expect contractors to know all these details themselves."

When Landmark moved to new offices this January, Knight provided desktop telephony services for procurement, IT, and shipping and receiving, but drew the line at moving senior management onto the system. "Given the value of the people and processes involved, we didn’t feel we could do justice to an IP installation at the moment," he says, though a switchover to an all-VoIP system is still scheduled during the next 18 months. Meantime, Knight is moving on another issue just as incrementally: introducing a small number of "softphones" that ring right on laptops or notebooks. "You can check into a hotel, plug in the laptop, start up the phone, and so far as anyone can see, you’re right in your office," he says.