Cox Communications, the local cable television system, has long been a key provider of high-speed Internet service, but it's preparing to enter another dimension of communications.

The cable company intends to start offering digital telephone service for local and long-distance telephone calls to a yet-to-be selected area of northwestern Las Vegas in October, Cox Vice President Steve Schorr said. Cox plans to expand the service to other areas of the valley as equipment is installed.

"We have spent millions of dollars upgrading our system in Southern Nevada, particularly in order to roll out digital telephone," Schorr said.

Cox has not priced its phone services, but Schorr said prices will be competitive with rivals' prices.

He identified Sprint as Cox's key competitor.

In a May 11 company statement describing the service's rollout in central Florida, Cox said the digital telephone service will use voice-over-Internet protocol, a technology that uses broadband Internet connections to transmit phone calls. But, unlike regular voice-over IP calls, Cox's calls won't travel on the public Internet; they instead will go over Cox's own national fiber-optic network, and if necessary, onto existing telephone networks.

Voice-over-IP services include voice, facsimile and voice-messaging applications that are made over the Internet, instead of a switched telephone service. Voice-over-IP is attractive to many phone customers because it provides low-cost long-distance service.

Sprint has been providing digital as opposed to analog telephone service over its land lines in Southern Nevada since 1986 and made its latest upgrade last year, said Scott Mitchell, operations director for Sprint in Las Vegas.

Several companies offer voice-over-IP service, including Vonage, AT&T and Nevada Telephone, a competitive local telephone exchange service. AT&T declined to comment on Cox's plans, and Vonage didn't return a call for comment.

Sprint Corp., the former monopoly local phone service in Southern Nevada, already provides voice-over-IP service to business customers. The company plans to offer voice-over-IP to residential customers, Mitchell said, but hasn't decided when it will introduce the service in Las Vegas.

While the cable company won't be Sprint's first competitor, Cox may be its strongest rival.

Both Sprint and Cox own "the last mile" of wire or cable leading to customers' homes and businesses, Mitchell said. Other companies typically need to use Sprint's or Cox's lines to reach customers.

"Anybody can jump into the business with a little bit of capital if (the customer) already has an Internet or broadband connection," Mitchell said. "When you have the entire network, you are going to be a more formidable competitor."

Cox owns cable lines that reach 680,000 residential and business customers in Southern Nevada. Of those, 400,000 rely on Cox for cable television and/or high-speed Internet access, Schorr said.

As a regulated utility, Sprint is required to offer telephone service to all locations in its Southern Nevada service area. Sprint is confident it will be able to compete based on price, quality and customer service, Mitchell said.

Nevada Utilities has been test marketing its own voice-over-IP service for a year. Spokesman Bob Jankovics counts 400 voice-over-IP customers at Nevada Telephone.

His company has installed equipment in all 11 central offices operated by Sprint in the Las Vegas area, and it has voice-over-IP equipment with "quadruple" redundancy, he said.

Nevada Telephone provides voice-over-IP service for $9.95 monthly. But Jankovics said he's ready to cut the monthly voice-over-IP fee to less than a dollar a month, if necessary, to maintain market share.

Jankovics doubts Cox or any other company can compete with Nevada Telephone on price, saying the company already has its own equipment and has no debt.

Nevada Telphone, however, relies on Sprint for lines to customers.

Because Cox already has cable leading to many homes and businesses in the Las Vegas area, it won't need to rely on Sprint to provide phone service between its own customers.

Cox will need to connect to Sprint's lines so its customers will be able to dial and receive calls from other phone company customers.

Unlike Sprint, whose rates for basic phone service are set by the Public Utilities Commission, Cox will be free to set its own rates.

Mitchell of Sprint said that regulated rates for basic phone service do not hamper Sprint, however, because the company bundles its regulated services with others that aren't regulated.

Like Sprint, Cox will provide "enhanced" 911 telephone service, which means a caller's address will automatically appear on a screen at the police and fire department dispatching office. Some voice-over-IP services don't provide 911, Schorr said.

Cox first introduced its digital telephone service in Roanoke, Va.

The company now also offers digital phone service in Tucson, Ariz., Phoenix, San Diego and Orange County, Calif., and 11 other areas of the country.

Jankovics of Nevada Telephone said voice-over-IP services won't really take off commercially unless telecommunications providers advertise the service extensively.

"I feel that (Cox is) going to educate the public. It's good for everybody, and it's good for competition, but I will not let them take hold," he said.