Peer-to-Peer (P2P) file-sharing has become the killer application in the Internet with respect to traffic volume which is even surpassing web usage. This characteristic makes P2P commercially attractive to network operators interested in increased traffic. In parallel, the demand for wireless services has caused wireless networks to grow enormously. We assume that P2P file-sharing will be mapped onto mobile environments by its users. This results in a mobile P2P file-sharing service. In this paper, we examine the feasibility of the eDonkey file-sharing service in GPRS and UMTS mobile networks, detect problems of the interaction between P2P and the mobile network, and outline first solutions to overcome them. The goal is the analysis of feasibility for an Internet-based file-sharing application in mobile networks and to provide real-world measurements. The measurements have been carried out in networks of two German GPRS network operators and, for the first time, for a UMTS network.