T-Mobile USA issued an upbeat assessment on Thursday about its testing for BlackBerry's new Z10 smartphone and said it hopes to become the first U.S. carrier to offer the handset by mid-March. "The device is more stable than we anticipated. If we are able to speed up the launch date, we will do that," said T-Mobile's Frank Sickinger. Also, BlackBerry said it will not launch BlackBerry 10-based smartphones in Japan, given the company does not view the country as a major market for its products. BlackBerry also named two new board members -- Richard Lynch, a former Verizon Wireless executive, and Bert Nordberg, who used to run Sony Ericsson.