A combined navigation and communication device (1) with mobile telephone module (2), integrated into the device (1), with telephone hands-free function, with a navigation unit (3) for route guidance and with a display unit (5), activated jointly by the mobile telephone module (2) and the navigation unit (3), is constructed in such a manner that the mobile telephone module (2) is used for receiving user-specific data from an external mobile telephone (20) and subsequently providing a user-specific mobile telephone function by means of the combined navigation and communication device (1).