These days your phone number is part of your identity, just like your street address or Social Security number. What if somebody took it from you?

That's what happened to Sunil Chohan of Brooklyn Park. In late May, his cellphone service stopped working. When Chohan asked why, his service provider said that the phone number he'd had for 12 years was no longer his, and that he couldn't easily get it back.

His 763 area code number had been transferred (or "ported" as the telephone companies say) from his service provider, Pure TalkUSA of Covington, Ga., to another cellular provider, Bandwidth.com of Raleigh, N.C. Both are small companies that buy space on larger networks such as AT&T or Verizon and sell it under their own brand.

Chohan, fearing identity theft, asked me what he should do. We agreed that he should report the missing phone number to the Brooklyn Park police, and that we should both e-mail the two phone companies for more information.

Pure TalkUSA said Chohan had authorized the phone number transfer. "The request included all verifying information," said Bethany ­Corvos, a company spokeswoman.

Chohan, who said he didn't make such a request, had joined Pure TalkUSA only two months earlier in order to get a more favorable rate plan than the one he had at AT&T.

"How can they allow this to ­happen, then keep telling me they cannot retrieve my phone number?" he asked. "Why is it that Pure Talk did not send me an e-mail requesting authorization for porting?"

Pure TalkUSA said it doesn't question porting requests because federal rules prohibit it from doing so. Bandwidth.com said federal rules prohibit the two phone companies from discussing the transfer of a customer's number.

It's unknown who asked that ­Chohan's phone number be ported. It's now being used by a Bandwidth.com customer whose identity wasn't disclosed by either company. Neither I nor Corvos was able to reach that customer.

The phone companies said Chohan will need to seek help from law enforcement to find out if his identity was stolen.

"We understand [his] frustration, but porting is a complex process with very specific guidelines mandated by the Federal Communications Commission," said Anna Kafka, a Bandwidth.com spokeswoman.

Under those rules, Chohan must ask Pure TalkUSA to request that Bandwidth.com port his number back to Pure TalkUSA's service. But that may be difficult, because to make the request Chohan must know all the details of the Bandwidth.com account for his telephone number — data to which he has no access because the account wasn't his.

He's likely to get his phone number back, but it's unclear just when.

Chohan's situation tells us this: Our cellphones depend on complex, largely automated networks whose actions are beyond our control. That's a great opportunity for ­identity thieves.

E-mail tech questions to steve.j.alexander@gmail.com or write to Tech Q&A, 650 3rd Av. S., Suite 1300, ­Minneapolis, MN 55488. Include name, city and telephone number.