Mobile phone networks say they will sue Ofcom to stop September’s upcoming auction of airwaves—the so-called 3G expansion band—until the regulator tells them explicitly how their existing 3G spectrum can be used, reports the guardian.co.uk. Last year, Ofcom proposed taking back more than a third of the spectrum used by Vodafone (NYSE: VOD) and O2 to sell to competing firms to run 3G services on it. The regulator believes that the refarming—as the process is being called--would bring high speed services to a larger population—especially those in rural locations. A decision was expected this summer, but thanks to the industry outcry, Ofcom’s head Ed Richards told a joint session of the Commons culture, media and sport, and business and enterprise committees last week that they would be forced to open a consultation on the issue instead. O2 and Vodafone have argued that if they do not know what they are allowed to do with their existing spectrum, they won’t be able to make plans for the upcoming 3G expansion band.