A mobile telephone system intended for indoor and outdoor subscriber use

Claim 1

A mobile telephony system intended for indoor and outdoor subscriber use, and comprising an external part-system for outdoor use which includes external base stations of relatively high signal strength and connected directly to a mobile switching centre, and an internal part-system for indoor use and having internal base stations of relatively low signal strength which are connected to the mobile switching centre, wherein - the two part-systems (6, 7) have traffic channels essentially for call transmissions and control channels essentially for assignment and change of the traffic channels; - at least one of the traffic channels of the internal part-system has the same frequency as the traffic channels of the external part-system; - the inner part-system (6) has adaptive channel assignement; - an internal identification word (IDI) which is unique to the internal part-system is transmitted from the internal base stations (BSI) on the control channels in the internal part-system (6); - an outer identification word (IDO) which is unique to the external part-system is transmitted from the external base stations (BS1, BS2) on the control channels in the external part-system (7); - a mobile station (MSI) detects a signal quality for the control channel of the internal part-system on which the internal identification word (IDI) is transmitted; - the mobile station (MSI) transmits an internal identification signal (IDIR) to the internal base stations (BSI) when the detected signal quality exceeds a desired quality measurement; and - wherein the mobile station (MSI) transmits an external identification signal (IDOR) to the external base stations (BS1, BS2) when the detected signal quality is beneath the desired quality measurement.