Prepaid operator MetroPCS Communications turned on LTE services in Boston, New York City and Sacramento today.

The company’s no-contract mobile broadband services are now available in nine metropolitan areas, including Dallas-Fort Worth, Detroit, Las Vegas, Los Angeles, Philadelphia and San Francisco. MetroPCS has plans to expand its 4G services into more metropolitan areas later this year and into early 2011, including Atlanta, Jacksonville, Miami, Orlando and Tampa.

“As the only no annual contract, pay-in-advance wireless service provider offering 4G LTE services, we continue to build our network to allow more customers to experience our unparalleled value and flexible, affordable service,” said MetroPCS President and CEO Roger Linquist in a press release.

The company will be competing against next-generation mobile broadband services from Clearwire, Verizon Wireless and T-Mobile USA in Boston and New York City, where the carriers have deployed WiMAX, LTE and HSPA+, respectively.

Information about what speeds customers can expect from MetroPCS’ LTE network have not been released. The company is deploying its LTE network in narrower spectrum bands than the services offered by Verizon Wireless, and it’s been speculated that its LTE speeds will be slower than those offered by its postpaid competitors.

Subscribers can get access to MetroPCS’ LTE services on the Samsung Craft, a LTE/CDMA phone with a 3.3-inch AMOLED display, slide-out qwerty keyboard and 3.2-megapixel camera. The device sells for $299 after $50 rebate.