Abstract: There is provided a method of coupling a telephone switched circuit network to an internet protocol network, wherein the telephone switched circuit network and the internet protocol network are interconnected by a gateway. The gateway comprises a non-routing key rule and the method comprises the step of generating a control method for a service by use of the non-routing key rule, wherein the service is located on the telephone switched circuit network and wherein the service is implemented by at least one application server, wherein the at least one application server is located on the internet protocol network and wherein the at least one application server is specified by an application server status. The method further comprises the step of sending the control message to a node, which is located on the telephone switched circuit network.