The White House will soon have to dial in a response to a petition asking that mobile phone users be allowed to switch locked devices to new carriers, a process known as "jailbreaking."

An obscure official's decision that the "jailbreaking" of phones violates US copyright law has generated a flurry of protests from civil liberties and digital rights activists.

A petition submitted to the White House generated more than 100,000 signatures as of Thursday, passing the threshold for a required response from the administration of President Barack Obama.

The issue arose from a ruling by the Librarian of Congress stating that those who circumvent the software protecting a mobile phone locked to a single carrier would no longer be exempt from copyright law as of January 26.

The decision could affect the widespread practice of "jailbreaking," or freeing a device sold by one carrier to be used on another, or while travelling overseas.

As a result, said the petition submitted to the White House website, "consumers will be forced to pay exorbitant roaming fees to make calls while traveling abroad. It reduces consumer choice, and decreases the resale value of devices that consumers have paid for in full."

"We ask that the White House ask the Librarian of Congress to rescind this decision, and failing that, champion a bill that makes unlocking permanently legal," the petition states.

Mitch Stoltz of the Electronic Frontier Foundation said the issue remains complex, and that while it does not make people who unlock phones criminals, it opens the door to potential lawsuits.

"While we don't expect mass lawsuits anytime soon, the threat still looms," he said in a blog posting.

"More likely, wireless carriers, or even federal prosecutors, will be emboldened to sue not individuals, but rather businesses that unlock and resell phones."

Stoltz said the law, known as the Digital Millennium Copyright Act, should be updated to fix the problem.

"The law was supposed to protect creative works, but it's often been misused by electronics makers to block competition and kill markets for used goods," he said.

"And no creative work is involved here: Wireless carriers aren't worried about 'piracy' of the software on their phones, they're worried about people reselling subsidized phones at a profit."