MetroPCS Communications is expanding its presence in the Northeast, adding more markets around the New York City area.

Specifically, the no-contract carrier announced that service has been added in Long Island, North Central New Jersey, White Plains and New Rochelle, N.Y., Stamford and Bridgeport, Conn.

The expansion includes two MetroPCS-owned retail stores, 50 authorized dealer locations and 15 Best Buy stores. MetroPCS says its expansion will bring 250 jobs to the area.

The company says consumer demand for its service and its entry into new markets like the Tri-State area have been driving factors behind its growth to more than 6.3 million subscribers nationwide as of the end of June.

Filling out its markets is important as the facilities-based carrier, which added new features to its $40 plan in July, seeks to compete with other prepaid carriers.

However, the company’s shares have taken a hit since it reported lower second-quarter earnings. Shares were trading around $7.97 early today after trading as high as $18.98 in the past year.

Shares in roaming partner and rival Leap Wireless International also have been down since it reported a wider second-quarter loss, trading around $15.99 compared with a 52-week high of $48.98.

Services like those offered by MetroPCS, Leap’s Cricket brand and TracFone were cited by CTIA as healthy indications of competition after the FCC last week said it would launch a wide-ranging probe into the U.S. wireless industry, including the state of competition.