CNAM is the abbrieviation for Caller Name. It is the SS7 service that runs behind the scenes to provide caller name. When a call is being completed (see ISUP) the destination SSP will check to see if the line being called subscribes to the CNAM service, if so the SSP will initiate a query to a SCP with the number of the person originating the phone call. The query will be routed through the STPs connected to the SSP and on through the SS7 network until it reaches the SCP. The SCP will look up the number given and return a response containing the name associated with the number. This will then be passed on to the caller ID box of the person recieving the call.