Efforts to bring 911 emergency telephone service to Northern Virginia -- the only missing link in a system already in operation in the District and the Maryland suburbs -- have collapsed.

Some officials close to the 2 1/2-year-old project say Alexandria's recent decision not to join 911 created a domino effect that led to Fairfax County's rejection of the system Monday. But other officials were harshly critical of the Cheaspeake & Potomac Telephone Co. of Virginia, which would have to provide equipment for the emergency system.

"Local jurisdictions in Northern Virginia weren't confident of the willingness and ability of C&P to be a full partner," said one official.

"Their [C&P's] performance was totally unreliable," said another. "It sure looks like they were trying to sabotage the system."

A C&P spokesman rejected those charges yesterday. "There is no question we were committed to 911," said R. Webster Chamberlin, the C&P official. "We were ready to install the equipment."

In fact, Chamberlin said the utility soon will present Northern Virginia localities with a bill for $250,000 worth of new equipment it has already purchased for the 911 system and that now won't be put in use.

Under the 911 system, all telephone calls for emergency public services such as fire, police and rescue services are made by dialing 911. Officials in the Northern Virginia suburbs say such a system would be especially helpful because of the myriad local agencies -- and different telephone numbers -- there.

The traditional method of dialing "O" for an operator is no longer effective because a caller, say in Fairfax County, could get a Washington operator unaware of which fire department is closest to his home, according to advocates of the 911 system.

A nationwide 911 dialing system for emergencies first was advocated by the President's Commission on Law Enforcement and Administrative Justice in 1967. The commission, like other supporters of the system, said a single three-digit number would mean calls for help could be made quicker and, in turn, would get quicker response.

An official in the Commerce Department's National Telecommunications and Information Administration -- the lead federal agency in the 13-year-old drive to make 911 the central emergency number throughout the nation -- yesterday blamed American Telephone & Telegraph Co. for the delays. "The question should be, why hasn't Ma Bell (AT&T) moved ahead?" he said.

The official, who, like other critics, declined to be named, said AT&T, although it has been formally committed to promoting 911 dialing for years, has been sending uncertain messages to its affiliates, among them C&P.

The Northern Virginia officials critical of C&P said the utility sent 17 different representatives to regional meetings on 911, but that not one of those delegates was present from the first to the last of the meetings.

They also said C&P officials failed to provide satisfactory answers on technical questions and earlier this year presented revised estimates that would have more than doubled the cost of 911 for Northern Virginia.

Some of the local officials blamed "corporate ineptitude," but two said they wondered if C&P wanted the system to fail in the hope that Northern Virginia localities later would opt for a more expensive, fully computerized system that will be available in two years.

As an example of C&P's attitude, one member of the negotiating committee said that when officials suggested the utility print brief emergency informatiopn in both Spanish and Vietnamese in its Northern Virginia directory, a company representative said, "If I went to Vietnam, I wouldn't find emergency information in English."

The so-called Basic 911 -- the system rejected by Alexandria and Fairfax -- would have cost about $30,000 to install and $72,000 to operate annualy according to Thomas Brannan, a spokesman for the Northern Virginia Planning District Commission, which coordinated negotiations. Brannan said the computerized system, based on some estimates, could cost $1 million to install and $250,000 to $500,000 a year to operate.

Said one local official who took part in the negotiations: "There's no profit in the basic system. It sure looks as if the company was hoping we would adopt the enhanced system."'

The enhanced system appears to answer the main criticism of the basic system -- that, because of where telephone exchanges are located, some Alexandria emergency calls would go to Arlington first, slowing response time. The much higher cost of the newer system, some local officials say, could rule out its adoption.

Emory R. Rodgers, a member of the 911 negotiating committee and chief of inspections in Arlington, said that the estmated cost of the enhanced system for his jurisdiction would be 300,000 to install and $32,000 monthly. "People will ask, if it costs that much, is it really worth it?"' he said.