a method for converging a call is disclosed . a non ip - multimedia - subsystem network is provided with a non ims network interworking device , by which the non ims network is converged with a voice over internet protocol 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 .