# Calling card service scenario

Applications that provide calling card services can use RTP switching channels to provide access to these services. A Fusion media server can set up and tear down RTP switching connections to connect calling card users with the outbound calls that they request. In this scenario:

Step | Action
1 | The media gateway application receives an incoming call from a calling card user through an RTP endpoint.
2 | The media gateway connects the user to an interactive voice response (IVR ) port through a voice channel and DS0 endpoint. The application then uses voice message prompts to elicit the number that the user wants to call.
3 | The media gateway application places an outbound call to the number that the calling party specified.
4 | If the gateway is successful in placing the outbound call, it creates two RTP switching channels to connect the original RTP endpoint with an RTP duplex endpoint associated with the outbound call. These endpoints can be IPv4 endpoints, IPv6 endpoints, or a combination of both.
5 | The application disables the voice channel associated with the IVR port.