The invention discloses a service processing method, service processing equipment and a service processing system. In the technical scheme, the method comprises the following steps: a first communication network acquires the subscription information of a user in the first communication network and instructs a second communication network to provide corresponding services for the user according toservice information subscribed in the second communication network by the user after judging that the user subscribes services in the second communication network according to the acquired subscription information. The service processing method, equipment and system can avoid the problem that a CS domain network user cannot use services provided by an IMS network in the prior art.