MetroPCS Communications, of Dallas, has filed to raise up to $1.125 billion in an initial public offering.

It is significant because only six IPOs worth $1 billion or more were seen in 2006, out of a total of 200.

The company, which provides wireless broadband personal communication services, claims 2.6 million subscribers, and reported net income of $70.6 million on revenue of $1.1 billion in the nine months ended Sept. 30.

Backers of the company include Accel Partners (holding 11 percent), First Plaza Group Trust, M/C Venture Partners, Madison Dearborn Capital Partners and TA Associates. These guys poured in a whopping $1.1 billion over the past 12 years. However, it is Accel that will profit the most, because they invested early, and got a large ownership in the company for relatively few dollars. Notably, Accel kept investing in the company, maintaining its large stake in MetroPCS, even through the bleak economic years of 2002 and 2003. Madison Dearborn and TA invested a huge $330 million each in late 2005 at a high valuation, so they may see profits immediately.