A vehicle communication system is disclosed, for use on e.g. trains, ferries and busses. The system includes an internal local area network (LAN) arranged within the vehicle; at least one antenna for wireless communication with external wide area networks (WAN) outside the vehicle; and a data communication router for providing data communication between said internal LAN and said external WANs. The data communication router includes a plurality of modems for communication with said external WANs, a subscriber identity module (SIM) pool including a plurality of SIMs, and a controller capable of periodically assigning SIMs within said SIM pool to any one of said modems. Hereby, a very efficient use of the modems and SIMs is obtained, leading to a less costly system and a more efficient communication.