SunCom Wireless, which has more than 1.1 million customers in the Carolinas, Georgia and Tennessee as well as the Caribbean, is officially part of T-Mobile USA.
The companies closed on their merger last week.
T-Mobile now offers service in 98 of the nation’s 100 largest metro markets.
SunCom was based in Pennsylvania. T-Mobile USA is based in Bellevue, Wash.
The Federal Communications Commission approved the merger on Feb. 8.