In theory, once added to the list, a phone cannot be activated on any U.S. carrier. But the system is not perfect. For it to work, phone users must notify their carrier of the theft and in some cases provide the IMEI themselves. There are also limitations to its scope. "The blacklist is good, but one of the easiest things we can do to make it more effective is more worldwide data sharing," said Kevin Mahaffey, CTO of mobile security company Lookout. "There is some sharing in different parts of the world, but not all operators share their lists."
In the United States, that's beginning to happen, said Chris Guttman-McCabe, vice president of regulatory affairs at the CTIA, an industry trade group. AT&T and T-Mobile, which share a common network technology, have a common database and all U.S. carriers plan to have a single database up and running by November that covers phones based on the new LTE cellular technology.
U.S. carriers have also begun supplying information to an international database that covers 43 countries, and the FCC has been talking to Canada, Mexico, and some South American countries about getting on board, said Guttman-McCabe.
So now, the main push is to educate users about the existence of the block list and get them to secure their phones with a password, screen lock, and software that can remotely track or wipe a stolen phone. Smartphone makers committed to include this information with new phones sold from the beginning of this year.
Even if universal, a global blocklist still would have shortcomings. While technically difficult, it's possible in some phones to rewrite the IMEI number, providing them with a new identity and bypassing the network lock-out.
What Congress and law enforcement is advocating
In an attempt to combat this, Sen. Charles Shumer (D-N.Y.) introduced a bill into the U.S. Congress last year (S.3186) that sought a five-year jail sentence for anyone who rewrites an IMEI number. The bill was referred to the Judiciary Committee, but it died when the congressional session came to a close.
"To me, while well intended, that's not necessarily where the solution is," said George Gascón, San Francisco's district attorney. "We already have way too many people in prison, we have enough laws on the books, and the last thing we want to do is continue to take young people and put them in prison for long periods of time. What we need to do is remove the marketability of these items," he said.