Method and device for blocking IMS (IP Multimedia Subsystem) business exception call

The invention discloses a method and device for blocking an IMS (IP Multimedia Subsystem) business exception call, and aims to solve the problem that vulnerability attacks performed by using the Transit function of the IMS in a network cannot be prevented in the prior art. The method comprises the following steps: receiving a request message of call forwarding sent by a query call session control entity, wherein the request message of call forwarding carries a called number, and is sent when the query call session control entity cannot acquire the user data of a calling number of call forwarding from a home subscriber server; checking the format of the called number carried in the request message of call forwarding; and when the format of the called number is determined to be inconsistent with a predefined strategy of call pass-through permission, terminating call forwarding.