Circuit domain call implementing method and system

The invention provides a method for realizing circuit domain paging, which is used for circuit domain paging a called subscriber device after saving a signaling function in a free mode introduced to a group domain; and the method comprises the following steps: when circuit domain paging is carried out, a mobile switching center/an access position register transmits a circuit domain paging requesting message to a group domain gateway which is recorded in Gs association relation; after the group domain gateway receives the circuit domain paging requesting message, circuit domain paging is initiated in the group domain, and the circuit domain paging is transmitted to the called subscriber device. The invention also provides a control system of circuit domain paging. The method and the system can support CS fallback under ISR without upgrading MSC of the current network, and the like, thus reducing the running cost and risk of the current network, ensuring the usability of the CS domain of UMTS/GSM network, reducing the deployment cost of an EPS network and being beneficial to quick application of the EPS network.