A routing method, apparatus, and communications system are provided. A routing method is applied to a network shared by multiple operators. The method includes: when receiving a service request message of a user terminal, obtaining, according to the shared resources occupied by the user terminal, the information about the operator to which the occupied shared resources belong from the resource configuration database; and matching the routing information in the connection route list according to the information about the operator to which the occupied shared resources belong, and forwarding the service request message according to successfully matched routing information. With the technical solutions, the operator to which the shared resources belong can charge for the call services of the user terminal.