Increasingly, carrying a smartphone means being a target. Commuters who doze on the Metro are targets for pickpockets, while pedestrians chatting on iPhones wear bull’s-eyes that attract armed muggers.

Police officials hope their newest resource — a voluntary agreement between the Federal Communications Commission and mobile service providers to disallow service to phones that are reported stolen — will help stem the tide. Local and national officials said Tuesday that they believe the ability to render phones nearly useless will eliminate the profit motive for robbery and theft targeting mobile devices.

“Any system that can prevent a theft or a thief from reselling a device will be a welcome tool to make our system safer,” said Metro Transit Police Chief Michael Taborn. New York Police Commissioner Ray Kelly called the database akin to “draining a swamp to fight malaria.”

More than half of the robberies reported to D.C. police since the fall involved smartphones, according to Police Chief Cathy L. Lanier, whose department has targeted rising robberies and thefts with undercover stings and increased patrols.

Taborn said his officers recorded 326 incidents involving the snatching of electronic devices in 2011 and traced stolen phones to malls in Northern Virginia. Undercover stings in which officers have posed as sleeping commuters have led to dozens of arrests.

In recent months, Lanier joined New York officials and other big-city police chiefs to lobby FCC Chairman Julius Genachowski in hopes of convincing service providers to take the step announced Tuesday.

Wireless carriers AT&T, T-Mobile, Verizon and Sprint, which serve 90 percent of smartphone users, agreed to implement a database of identification numbers embedded in phones. When a victim reports a stolen phone, its number will be placed in a database and service will be denied the next time someone tries to use the device, officials said.

“Working together, we have come a long way in a short time,” Genachowski said.

Philadelphia Police Commissioner Charles H. Ramsey, president of a national police chiefs association that lobbied alongside Lanier, said he hopes the database will help make streets safer.

“In most instances these devices are being taken at the point of a gun,” said Ramsey, who was D.C. police chief from 1998 to 2006. “I’m thinking this is going to make a difference across the U.S.”

Wireless carriers said they will launch the database in six months. Genachowski said that if they do not, regulators might seek legislation requiring them to create it.

The database is not a cure-all, said Sen. Charles E. Schumer (D-N.Y.), who pressed the cellular industry and the FCC to adopt the system. Savvy thieves could “wipe” a phone’s ID number, making it operable again.

Schumer has said he plans to introduce legislation that would make such modifications a federal crime. “We always have to be one step ahead of the criminals,” Schumer said.

Officials also said they would try to convince foreign carriers to adopt the system, which is already in use in Britain and Australia.

At the street level, Lanier said she remains committed to investigating thefts and robberies and making arrests even as the database is established. “We’re not going to let up,” she said.