T-Mobile USA’s chief executive Philipp Humm has abruptly resigned from his position today, according to the company.

We don’t know the exact reason for Humm’s departure, but T-Mobile did say he was interested in pursuing a career outside of T-Moblie parent company Deutsche Telekom. If I had to make a guess as to why he’s leaving, it would probably because being CEO offers him little in the way of career growth.

T-Mobile is the fourth largest wireless carrier in the U.S., and it was unable to merge with the nation’s second largest carrier AT&T last year due to the sale being blocked by federal regulators. Under Humm’s direction, T-Mobile did come out ahead in that deal, but beyond that, the carrier’s growth potential is rather limited. Not only does T-Mobile have to pay for expensive speed upgrades to its wireless network, but it also may never come close to surpassing its nearest rival Sprint (the third largest carrier in the U.S).

While T-Mobile searches for someone to fill the position, COO Jim Allings will take over Humm’s duties. Meanwhile, Humm is said to return to Europe, which is where his family still lives.

Via AllThingsD; Photo by Sean Ludwig