AT&T said Monday it was implementing a system to block the use of stolen mobile phones, as part of an effort by US carriers to crack down on theft of smartphones.
"As announced in April, AT&T is creating a stolen phone database to prevent devices reported stolen from accessing wireless networks," carrier spokesman Mark Siegel said.
"We will install this availability this week for AT&T phones on our network and are working toward a cross-carrier solution later this year."
The move came after US authorities and cellphone carriers announced an effort in April to limit incentives to steal smartphones, which can be worth hundreds of dollars.
The major carriers and the Federal Communications Commission answered rising pressure from US police departments with a plan for a national database for stolen phones that would prevent their use by new owners.
The four leading carriers had agreed to set up their own databases of stolen phones within six months, and aim for a common registry within 18 months.
Officials said that in some major cities, 40 percent of all robberies now involve cellphones.
The aim is to allow customers to easily report a stolen phone with carriers that will then refuse to activate it under a new owner -- rendering it unusable and worthless to thieves.