Vonage already sells off-the-shelf starter kits at Best Buy, OfficeMax and other major retailers.

Now a Cary outfit will start selling voice over Internet protocol service at more than 240 CompUSA outlets. CompUSA begins selling Bandwidth.com's VOIP service for small and medium businesses April 25, including at its store in Raleigh.

For Bandwidth.com, a private company that employs 69 people in Cary and two in Chicago, the nationwide exposure represents a potential gold mine of customers.

For two years, Bandwidth.com has been offering VOIP phone service to small and medium businesses directly and through IBM, Intel and others. The company is preparing to hire as many as 60 employees this year to handle the CompUSA account as well as other growth.

"This is another step in the mainstreaming of the VOIP market," said Rich Tehrani, editor and publisher of Internet Telephony magazine. "You're getting a virtual phone system."

VOIP generally costs less than traditional phone service and offers more features. VOIP service sends phone calls over the Internet as if they were e-mail, and requires high-speed Internet access.

The financial terms of the partnership between CompUSA and Bandwidth.com are not public, but they are based on a revenue-sharing agreement, said Henry Kaestner, chief executive of Bandwidth.com.

Kaestner, a former commodities trader on Wall Street, formed Bandwidth.com in 1999 and branched into VOIP 22 months ago. The company also provides network management services and resells Internet access.

In selling through third parties, Bandwidth.com expands its reach but gives up some control. For example, its partners do not let the company disclose how many customers it has through these affiliations, Kaestner said.

The VOIP service will be promoted at CompUSA stores by service representatives called "techknowledgists" who also sell a host of other products and services. The Bandwidth.com product will also be installed by CompUSA technicians, Kaestner said.

Bandwidth.com will provide technical backup, installation scheduling and customer service, but onsite repairs will be handled by CompUSA.

Even when the VOIP customer contacts Bandwidth.com for help, those inquiries will be handled by a team dedicated to the CompUSA account.

It hasn't been decided how Bandwidth.com representatives will identify themselves, but customers may think they're talking to a CompUSA worker, Kaestner said.

That's a different approach than the one taken by FeatureTel, a Morrisville VOIP company. FeatureTel's niche is selling to companies with offices in North Carolina that can be serviced in person by FeatureTel's three technicians in the state, said Paul Levering, FeatureTel's CEO.

VOIP services differ in other ways, too. While Bandwidth's VOIP service is installed by professionals, while the small-business service offered by Vonage is sold through a starter kit designed to be installed by the customer.

Bandwidth.com's VOIP service lets customers access voice-mail messages from their computer, and then forward those messages using the keyboard, in essence sending a sound file by e-mail. An advanced call-forwarding feature allows customers to program the service through a Web site to send calls from some callers into voice mail and forward other calls to the customer's cell phone or home phone.

Southwest Durham Family Medicine switched to VOIP as a cheaper way of getting voice and data services from the same company, said David Brooks, manager of the six-employee medical practice. Brooks described the service quality as excellent.

"Sometimes it's so clear on the phone, there's no static, and people think the call's been dropped," Brooks said.

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