No promises, but the upcoming U.S. 700MHz spectrum auction might unleash some new freedoms for U.S. cellular customers.

The service description for the 700MHz spectrum, about to be vacated by analog television, is to be completed within the next month. Auctions are to begin no later than January 2008 with services to follow.

There’s a chance that the FCC, which controls the auctions, might license the spectrum with the condition that bidding would-be operators will sell at least some unlocked phones. Such phones allow users to load their own application software on them.

U.S. mobile network operators currently lock their phones, against use on other providers’ networks and against the use of third-party application software and features unapproved by the carriers. Mobile carriers often turn off features that handset manufacturers build into their devices that compete for cellular airtime minutes.

VoIP company Skype—with a vested interest in getting its renowned IP telephony software client onto mobile phones—feels the FCC should do something about these restraints, which the company contends stifle handset innovation and competition. In a petition filed with the FCC early this year, Skype drew a mobile analogy to the 1968 Carterfone decision, which allowed third-party devices to connect to the then-monopolistic AT&T network. The liberating decision led to the birth of modems, answering machines, fax machines, and many other telephony devices.

Christopher Libertelli, senior director of government and regulatory affairs, says, “Keep an eye on the 700MHz auctions. Carterfone could come up in the proceedings.”

Dave Passmore, research director at the Burton Group in Sterling, Va., acknowledges that it “would be more fair” to carriers if the government put operational terms on spectrum at the time that licensing occurs, rather than going back and changing the rules for current licensees.

For their part, the mobile carriers, as represented in rebuttal comments to Skype’s petition by the CTIA wireless association, feel plenty of wireless competition exists already and that additional rules would require costly government enforcement. The CTIA’s counter petition also indicates that the unmonitored use of third-party software could impede the carrier’s ability to control user service quality.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.