One Bronx company is betting that its “cyberdoormen” will soon be remotely manning the doors of small- and medium-size apartment buildings around the city.

Cyberdoormen – increasingly popular with the city’s developers – are not the steel humanoids once imagined in science fiction movies, but a network of cameras, intercoms, card access points, and alarms linked by high-speed Internet to a remote 24-hour monitoring location.

Currently, seven Manhattan properties are using the technology, and 12 more are under contract to install the systems. An executive of the company selling the service, Best Monitoring LTD, Seth Barcus, said he expects that within three years more than 30 buildings will employ its cyberdoormen.

“We are targeting those buildings with 30 units or less that are too small to afford a real doorman,” Mr. Barcus said. “We are never going to be handing you a paper in the morning. But they are taking us on because the security access is great.”

A spokesman for the city’s building workers union, Local 32BJ of the Service Employees International Union, Matthew Nerzig, said he was not concerned about the new technology replacing some of the city’s approximately 5,000 doormen.

“There is no way of replacing a doorman, particularly in the post-9/11 era,” Mr. Nerzig said. “No matter how you look at it, a building will be safer a human being in front.”

The way the cyberdoorman system works, when visitors ring an outside buzzer, they are connected in real time video to a security guard at a facility in Hunts Point in the Bronx. The guard will call the appropriate residence and either buzz in the visitors or turn them away.

“Part of the mystique of the whole cyberdoorman thing is that nobody knows if the doorman is at the building or not, and that adds another degree of security,” Mr. Barcus said.

The system also allows remote access to building lobbies for deliveries, pickups, and maintenance. Dry-cleaning or FreshDirect deliveries can be stored in a storage room in the lobby without letting unsupervised deliverymen into the building.

The developer of 14 luxury apartments at 88 Washington Place in the West Village, Alan Friedberg, opted for the cyberdoorman system and has advertised it as an amenity to buyers. Mr. Friedberg said that a full-time staff of about four doormen would cost the building about $250,000, or nearly $18,000 a year for each apartment.

“Common costs are very critical,” he said. “And that’s too expensive.”

The developer paid about $50,000 to install a premium version of the cyberdoorman system and will pay about $8,000 a year for the security monitoring service. Cheaper systems are available for about $10,000.

Mr. Friedberg said at some future date residents may opt to hire a human doorman for an eight-hour shift, but that would not interfere with the system. The developer expected the system to be popular with the dozens of smaller luxury residential apartments in the development pipeline.

The first cyberdoorman system appeared more than three years ago, but Best Monitoring has tinkered with the technology to improve connectivity, increase response times, and reduce service disruption. Best Monitoring is a 20-year old security company with more than 1,300 clients. The company is talking with lawyers about patenting the system, but Mr. Barcus said that obtaining a patent is complicated because the system is merely a creative reuse of existing technology.

Best Monitoring has marketed the system by reaching out to large brokerage firms like the Corcoran Group. Mr. Barcus says that brokers who become familiar with the technology will be more likely to introduce it to developers of new properties. Mr. Barcus said that so far word of mouth has been his best advertising tactic, and no customer has canceled a subscription.

He said the security systems have warded off drunk buzzer-pressers and called the police to collect potential intruders. Mr. Barcus said the Bronx team of security guards has directed firefighters over the intercom system.

Residents who miss the human touch will ring the intercom on their way outside and say hello, or goodbye, to the off-site security guard on duty, Mr. Barcus said.

In the future, Best Monitoring hopes to expand the technology to office buildings, warehouses, and even to nanny cameras, a method for parents to monitor their children and their caregivers.

“With nanny cameras, most of the time you find out after the fact,” Mr. Barcus said. “The parents want us watching that kind of thing in real time.”