At the urging of Prince George's County police officials, the County Council is considering outlawing automatic security systems that summon police when an alarm is activated.

Police say the devices result in too many "unknown trouble" calls, in which officers respond without knowing what type of help is needed. Such calls often turn out to be a waste of police time, officials said.

Proposed legislation would prohibit the use and sale of devices that, when triggered, dial the 911 emergency number with a recorded call for help. It would also ban security systems that rely on monitoring stations to call 911.

While no one is certain how many alarm systems are in use in the county, one security company owner estimates that one of every 40 homes in Prince George's uses an alarm system connected to a monitoring station.

Under the bill, introduced by Council Chairman William B. Amonett at the request of County Executive Parris Glendening, monitoring stations would be able to notify police only after contacting property owners by telephone to find out what kind of assistance is needed.

The bill is pending before the council's Human Resources Committee, which has jurisdiction over police matters.

Capt. William Johnson, commander of the county police communications section, said there has been an increase in the number of "unknown trouble" calls from direct-dialing devices and monitoring stations.

"The whole idea is not to avoid providing assistance, but to respond with the right equipment, in the right way," Johnson said.

Under the current system, Johnson said, personnel from monitoring stations often provide too little information when alerting police. "We have no idea what they need the police for," he said. "Is it a residential robbery? Is it a burglary? The officer has no idea what he's expected to do when he gets there."

Every "unknown trouble" call gets the same response, officials said: At least two marked patrol cars speed to the destination using their sirens and flashing lights. When police responded to one such call recently, it turned out to be a homeowner testing his alarm system, Johnson said.

Such false alarms, he said, "increase the possibility that officers get to the point where they may not take these calls as seriously. Their response is going to be more lackadaisical, they are not going to get there as quickly."

Robert Arscott, a retired District police officer who is president of Sting Security Inc. in Temple Hills, estimated that for every 400 automatic alarms his company monitors, only one may require police intervention. His company screens out about 300 of those calls before notifying police, he said.

"It's a 'cry wolf' situation," Arscott said. "I understand the problems the police are having."

But in general, security companies and alarm system owners are upset about the proposed legislation, which they say would leave property vulnerable. Companies say it would be too costly for security personnel to check every alarm.

"They want somebody to call me if the alarm goes off before they send the police," said Laura Elrod, who has a security system in her house in southern Prince George's County. Intruders "could kill me in the meantime," she said. "What the heck do I have an alarm system for if the police can't respond?"

The prices of alarm systems range from about $150, for owner-installed, direct-dial models, to $1,500 or more for more elaborate systems, said Dallas Johnson, legislative vice president for the Mid-Atlantic Alarm Service Association. Security companies charge $15 to $25 a month to monitor the systems.

In a letter to the County Council, Glendening said security systems that use monitoring stations provide little advantage over simply dialing 911.

"We maintain a 24-hour, trained monitoring staff that is experienced in talking to people in stressful situations, determining their needs and often giving valuable life-saving instructions over the telephone," Glendening said.

Dallas Johnson said the bill renders useless most alarm systems used in businesses and homes in the county, systems that are legal in other metropolitan Washington jurisdictions. "It shows the burglar that he doesn't have to worry about anything," Johnson said. "If there isn't anybody home, police won't respond to the alarm. If there is somebody home, all he has to do is stop the person from answering the phone."

The county fire department, which is supporting the legislation, has similar problems when monitoring stations report a fire without giving detailed information, a spokesman said.