The present invention discloses a method and a system for implementing communications between multiple subnets covered by one physical Mobile Switching Center and an MSC. The method maps the MSC to multiple virtual MSCs that are logical MSCs within the physical MSC, each virtual MSC corresponds to one subnet that represents one or more location areas within the physical MSC, assigns to each of the multiple virtual MSCs a virtual MSC number, identifies a virtual MSC number of one of the virtual MSCs that is currently visited by the wireless mobile terminal, according to the current location area and the set relationship between each subnet that represents one or more location areas within the physical MSC and each virtual MSC number, and transmits the identified virtual MSC number of one of the virtual MSCs that is currently visited by a terminal when the wireless mobile terminal implements communications.