MetroPCS officially flipped the switch on its Advanced Wireless Service (AWS) network in Philadelphia today, marking the beginning of a northeast expansion that will almost double the size of its footprint and expand into three of the largest metro regions in the US by 2009.

Metro is now offering its all-you-can-eat local and long distance calling plans from six company-owned stores and 132 independent retail outlets in the greater Philadelphia area as well as its Website. And it plans to expand to additional locations by the end of the year. The launch is the third Metro has undertaken using the AWS spectrum it acquired in the FCC’s Auction 66 two years ago. Las Vegas and Shreveport, La., launched earlier this year.

The carrier is moving quickly into its new markets while carriers typically are delaying new network launches. The Las Vegas launch beat its second-quarter target by weeks, and Metro originally announced it would launch Philadelphia by the end of the year. Instead the network went live just two days into the third quarter. Its next big market, Boston, is scheduled for the first quarter of next year. The crown jewel, New York City, is targeted for the second quarter. But at its current pace, Metro might have one or both markets live by the end of the year.

While Metro solely uses CDMA technology, the AWS band uses different frequencies than the PCS band it uses in most of its West Coast, Southwest and Southeastern licenses, which has required Metro to procure special dual-mode phones to support both types of networks. As new CDMA AWS phones become available, Metro and fellow AWS-winner Leap Wireless are adding them to their portfolios. Metro has said it hopes to have its entire handset portfolio converted to dual-mode devices by mid next year. By the end of its expansion spree, Metro’s footprint will cover 100 million pops, about one-third of the US population.

Last week, Metro launched a new program called MetroFlash, which allows customers from Sprint, Verizon or other CDMA operators with compatible handsets to bring their phones to the Metro network. MetroFlash, however, won’t work in the new Northeast networks, nor in Las Vegas, since Sprint and Verizon do not sell dual-mode AWS-PCS phones.