The California Highway Patrol continues to scratch its collective head as to why someone is calling Bay Area cell phone customers under the caller identification "911 Emergency."
However, they do know how it is being done.
It’s a technique called "spoofing," and it allows a caller to change the caller identification associated with his or her number.
Since Saturday, police stations and other emergency services havebeen receiving calls from confused cell phone users who are seeing missed calls from "911 Emergency" or similar identifications. Some have been receiving the calls in which a police officer impersonator says there is a warrant out for the person’s arrest or there is an emergency at their home.
A number of pay services, such as Spooftel, Spoofer and Spoof Card, offer caller ID spoofing. Some of these services control the numbers that can be entered as spoofs, for example by restricting the number of digits that can be entered, but some do not.
"Anyone who really wants to can make caller ID say anything," co-founder of People For Internet Responsibility Lauren Weinstein said. "It’s the interface between the customer and the network that makes the assumption that there’s honest [caller ID] information being provided."
Most of those affected have been customers of MetroPCS, but Verizon and Nextel subscribers have also been affected, according to the CHP. The majority of reports are coming from around the East Bay, especially in Pittsburg, but customers in San Francisco, Monterey and Riverside counties have also been affected.
The California Highway Patrol’s Linda McNeill, a telecom systems analyst, stressed that no law enforcement agency or other emergency service would register as 911 on caller ID.
"Usually, when the Highway Patrol calls a citizen, you will either get our public number displayed or some other seven- to 10-digit number that could be dialed," she said.
Mary Pat Marshall, director of communications for the CHP, said people should verify who they’re talking to before revealing any personal information.
"If the caller calls and says, ‘I’m a caller with such and such police agency,’ perhaps they need to call that agency back on a published, nonemergency number to verify the information," she said.
MetroPCS spokeswoman Karina Carretero said the company was fully cooperating with the investigation.
"We take every customer concern with the utmost seriousness and would encourage any of our subscribers that receive a suspicious call like this to contact their local police department," she firstname.lastname@example.org