Process and system for automatic routing

A system for routing in the connection setup for calls between a first subscriber and a second subscriber, a call being initiated by the first subscriber by selecting a telephone number and being directed to the second subscriber who moves between coverage areas of mobile switching centers of a public mobile radio telephone network and areas of private branch exchange of at least one private network and uses at least one radio telephone subscriber station for receiving and transmitting the calls, comprising:

• means in the private network for setting up a connection to a first private branch exchange based on a selected telephone number and for sending a mobile subscriber telephone number from the private branch exchange to the public mobile radio telephone network;
• means in the public mobile radio telephone network for storing at least one identification number with which the private network is identified for access to the private branch exchange of the private network;
• means in the public mobile radio telephone network for offering a routing number based on the incoming mobile radio telephone subscriber telephone number and means for checking a routing number with reference to the stored identification number as to whether the call destination lies in an area of a private branch exchange of a same private network to which the first private branch exchange belongs;
• means in the public mobile radio telephone network for clearing down the call given identity of the private network for the first private branch exchange and for the private branch exchange of the call destination, and for sending routing information that define the call destination to the first private branch exchange the private network, which sets up the connection to the call destination in the private network based on the routing information.