A method for converging a call is disclosed. A non IP-Multimedia-Subsystem (IMS) network is provided with a non IMS network interworking device, by which the non IMS network is converged with a Voice over Internet Protocol (VoIP) network. The method further includes: when the non IMS network determines that a callee receiving a call request is a convergence call user, the non IMS network forwards the call request to the VoIP network; and the VoIP network initiates a call to the callee. A system for converging a call which implements the aforementioned method is further disclosed. The disclosure takes full advantage of the service characteristic of the convergence network, so as to supply users with convenient service access implementation and reduce the service charge.