A coordinate-measuring system and related method for securely and intelligently coupling and connecting a mobile terminal device to a stationary coordinate-measuring device. A mobile terminal is arranged to be physically separate from and movable in relation to the coordinate-measuring device and is designed for the operation of the coordinate-measuring device. The coordinate-measuring device and the mobile terminal are designed to establish an authenticated wireless connection for exchanging data between the coordinate-measuring device and the mobile terminal. An identifier, which uniquely identifies the coordinate-measuring device, and a dynamic first key are associated with the coordinate-measuring device. The dynamic first key represents an access authorization and preferably also a degree of access authorization of the user. The mobile terminal device is also designed to request the first key from the user. The first key is used for authentication in the establishment of the wireless connection.