Lanier said victims of cellphone theft can contact their providers and have their phones remotely disabled, rendering them useless.
At the Monday news conference, Gray (D) and Lanier announced the launch of brickit.dc.
gov, a Web site dedicated to helping victims of cellphone theft.
The site contains links with directions on how to have a stolen phone disabled.
In April, the nation’s largest wireless carriers agreed to help crack down on cellphone thefts by creating a database to identify and disable stolen phones.
Cellphones, tablets and similar electronic devices, which often cost hundreds of dollars, are a target for thieves seeking high-value items that can be easily resold.
Police have said they hope to combat the thefts by eliminating the secondary market for stolen devices.
“This is not the end of the battle by any means,” she said.
Robberies of cellphones have declined since earlier this year, Lanier said.
In February, such robberies were up 46 percent over the same time a year earlier, according to the chief; as of this week, those robberies are up just 1 percent over last year.
She credited anti-theft efforts in general — police have used undercover patrols, decoy “victims” and other strategies this year — for the decline.
With the holiday shopping season underway, Lanier also discussed police plans for the coming weeks. There will be 81 additional uniformed officers patrolling, she said, in addition to plainclothes officers around.
Lanier encouraged residents to try to prevent themselves from being easy prey. Women shouldn’t hang purses on the backs of chairs, she said, and men shouldn’t keep wallets in their back pockets.