Mobile communications systems and interconnections strategies for use between different networks and different tariffs of such systems

A communications system including a communications network having mobile subscribers whose locations are variable, the communications network including means having knowledge as to the location of each of the mobile subscribers, and the communications network including a plurality of series connected mobile-services switching centres;

• and a PSTN (Public Switched Telephone Network) fixed network including a plurality of series connected first switching units, each of which PSTN fixed network first switching units is interconnected with a respective mobile services switching centre of the communications network via a respective interconnect whereby the PSTN fixed network and the communication network are interconnected at multiple interconnect points, wherein calls are set up between the said networks either by said mobile subscribers or by subscribers to the PSTN fixed network and multiple tariffs are applicable, the tariff employed for any particular call being determined by the location of the mobile subscriber involved in the call and being distance related, the same tariff being employed irrespective of the call set-up subscriber, and wherein for a call set-up to a mobile subscriber by a subscriber to the PSTN fixed network, the location of the mobile subscriber involved in said call is determined from the communication network's knowledge means and the one of said multiple tariffs corresponding to the location of the mobile subscriber involved in said call employed.