The higher regional court of Hamburg (Hamburger Oberlandesgericht) yesterday ruled in favor of T-Mobile. Sipgate is not allowed to promote or distribute its iPhone application that allowed Voice-over-IP (VoIP) telephony on jailbroken iPhones anymore.
The issue is not the application, but installing Sipgates VoIP client required to jailbreak the iPhone. And jailbreaking of T-Mobile’s customer’s iPhones is illegal in germany. By the way: jailbreaking of iPhones bought abroad is not.