T-Mobile USA, a unit of Deutsche Telekom AG , said its chief executive, Robert Dotson, will leave the company in May 2011 and named Philipp Humm as its designated successor.

Humm, who will be chief executive designate effective July 1, will take over as chief executive of T-Mobile USA in February, the company said in a statement.

Dotson will remain on as a T-Mobile USA non-executive board member until May 2011.

Dotson, who has served the company for 15 years, intends to devote more time to family and to pursue new opportunities, he said in a statement.

T-Mobile USA, once prized as Deutsche Telekom's growth engine, struggled with a high rate of customer cancellations in 2009 and trailed bigger rivals in building high-speed services. As a result, Deutsche Telekom has been searching for the right strategy for the distant No. 4 U.S. mobile service.

(Reporting by Shrutika Verma in Bangalore; Editing by Dan Lalor)