The head of Deutsche Telekom’s mobile telephone subsidiary has quit the company less than a month after the German telecoms group reported it was unhappy with the performance of the unit.

According to DT, Lothar Hunsel resigned as chairman of the T- Mobil subsidiary for personal reasons. But his decision is understood to have reflected disappointment in the unit under his control. DT’s T-Mobile has come under increasing competition from the D2 digital network owned largely by the Mannesmann industrial conglomerate. Gerd Tenzer, a main board member with responsibilities for telecoms networks, is to take over as temporary T-Mobil Chairman with Josef Brauner taking on sales and marketing activities. T-Mobile has approximately 3.5 million customers using its digital and analog services and domestic revenues of about DM 5.4bn ($3.1bn).