April 12, 2010 - Germany kicked off a multi-billion euro mobile spectrum auction on Monday, its largest allocation of frequencies ever.

The auction was launched at 1200 GMT and will be held in former military barracks in a suburb of Mainz, some 40 kilometres south of Frankfurt.

The auction is unlikely to be as lucrative as the one for UMTS licences a decade ago, which led to a bidding frenzy amid the height of the tech bubble and raised 50 billion euros ($67.98 billion).

Here are questions and answers on who's bidding, how the auction works and what the frequencies are used for?