The U.S. Senate may soon vote on surveillance reform legislation that would end the National Security Agency’s automatic collection and five-year retention of American call records. If the bill passes, it could push privacy-conscious cellphone users to switch service providers in hopes of keeping their call records out of government hands.

The White House-backed USA Freedom Act would require companies to supply call logs of intelligence targets and those of their contacts to authorities as needed. But companies would not need to keep logs longer than they do now, and authorities would need court approval to search records.

The major U.S. cellphone service providers currently have wide-ranging record retention policies, offering surveillance-wary customers – or those who may have ordered pizza from the same shop as a terror suspect – a range of privacy options.

A federal regulation requires landline providers to store call detail records 18 months, but wireless companies store the records for shorter – or significantly longer – periods of time.

Verizon Wireless, the country's largest cell service provider, keeps call detail records for about one year, a company spokesman says. Second-place AT&T holds them "as long as we need," according to the company's website, though AT&T spokesman Michael Balmoris tells U.S. News the retention period is five years.

T-Mobile holds call records between seven and 10 years, spokesman Viet Nguyen says. MetroPCS maintains separate records and keeps them two years.

Sprint holds call logs 18 months, spokeswoman Stephanie Vinge Walsh says. U.S. Cellular holds records one year, according to spokeswoman Katie Frey.

There are a number of other cell service providers that lease network space from the five major operators.

TracFone Wireless, the largest such provider, tells U.S. News in a statement that the company doesn't “comment on matters related to customer data and records.”

Credo Mobile, a smaller company that uses space on Sprint’s network, keeps records three years. The self-branded "progressive" firm finances a highly active advocacy group, Credo Action, which lobbies against surveillance laws like Section 215 of the Patriot Act – a provision that both the Bush and Obama administrations used to justify bulk phone record collection.

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“All carriers should aim to minimize their storage of telephone customer metadata to the extent allowed by law, especially in light of the current debate in Congress over reauthorization of the Patriot Act Section 215,” says Becky Bond, vice president of Credo Mobile.

“As a telecom that can be compelled by the government to participate in unconstitutional spying on Americans, we urge the Senate to fight to sunset Section 215 of the Patriot Act and oppose the USA Freedom Act,” Bond says.

At least one cellphone service provider does not keep records of customers' calls and therefore cannot be forced to provide them to authorities.

FreedomPop, which says it's nearing 1 million customers, leases space on Sprint’s data network. Similar to the Internet service Skype, it uses technology for calls known as Voice over Internet Protocol, or VoIP, that shields customers from such requests, spokesman Tony Miller says.

One of FreedomPop’s products, the encrypted and so-called Snowden phone, was marketed in direct response to the bulk records collection exposed by whistleblower Edward Snowden in June 2013.

The Freedom Act would, its backers say, end the bulk collection of call records, but many civil libertarians prefer that Section 215 expire as currently mandated on June 1 rather than be modified by the bill. Many privacy advocates voted against the Freedom Act when it passed the House of Representatives on May 13. Others support the act, however, pointing out bulk collection might migrate to another legal authority – such as another section of the Patriot Act – if the bill does not pass.

There’s no guarantee the Freedom Act will clear the Senate, where it failed to reach the 60-vote threshold for consideration last year and Majority Leader Mitch McConnell is pushing instead for a clean extension of Section 215.

Sen. Dianne Feinstein, a California Democrat who plans to vote for the Freedom Act, says her backup plan in the event of an eleventh-hour impasse is legislation that would force wireless companies to store records longer than they currently do – an idea vigorously opposed by privacy advocates that also may legally entitle telecom companies to compensation.

“It’s particularly important now that companies be allowed to compete for their customers over privacy, and to compete for their privacy you have to be able to offer less data retention, offer more secure services, and the government shouldn't be in the business of telling those companies what services they're allowed to offer,” says American Civil Liberties Union staff attorney Alex Abdo, who successfully argued the collection is illegal before a panel of the U.S. Court of Appeals for the 2nd Circuit. The panel found earlier this month that Section 215 doesn’t authorize the program.

Failure of the Freedom Act and continuation of the bulk collection of call records wouldn’t be a total loss for privacy advocates, though. In fact, it likely would provide better footing for lawsuits like one from the ACLU seeking a declaration that the practice is unconstitutional and a fundamental modification of the existing third-party doctrine – the legal argument that Americans have no reasonable expectation of privacy regarding information voluntarily shared with companies. Passage of the Freedom Act could kill some or all of those cases, two of which are awaiting appeals court rulings.

Government officials defending Section 215 bulk collection in court have largely refused to acknowledge that any of the major cellphone service providers are affected by secret court orders requiring them to turn over customer call records, saying Verizon Business Network Services – the company affected in a court order leaked by Snowden – is the only confirmed entity impacted.

But officials also have made little effort to deny the data collection is happening, and U.S. District Judge Richard Leon in 2013 surmised Verizon Wireless had been affected, granting standing for a lawsuit from legal activist Larry Klayman and finding the collection likely violates the Fourth Amendment.

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Though surveillance by federal agencies like the NSA has animated public debate about the privacy of phone records, the storage time by cell providers can come into play in routine criminal cases and civil lawsuits as well.