8:35 AM -- As the big German spectrum auction heads into week five, the bidding has just passed the €3 billion (US$3.9 billion) mark after 161 rounds.

Total bids so far on Monday morning came to €3.09 billion ($4.02 billion), and the bidding is still going on among the four participating German operators -- E-Plus Mobilfunk GmbH , Deutsche Telekom AG (NYSE: DT), Telefónica O2 Germany GmbH & Co. OHG , and Vodafone Germany .

The 800MHz frequency band has attracted the highest amount of bids at about €2.6 billion ($3.4 billion). While this spectrum is perceived as the most valuable for Long Term Evolution (LTE), it also has some special strings attached for coverage obligations. Operators that acquire spectrum in the 800MHz band will have to roll out mobile broadband networks in rural areas in Germany that have poor broadband access. The license obligations require operators to cover 90 percent of these areas before they can roll out mobile broadband in other areas using this spectrum, according to a Bundesnetzagentur (BNetzA) spokesman.

The latest auction results are posted here.

— Michelle Donegan, European Editor, Light Reading Mobile