The system fully supports validation of roaming calls. When a roaming call (see diagram) is being done, the terminating network receives roaming call details and is reaching out to A-number's original network to check if it's in roaming status. A-number's original network confirms it, thus completing data necessary for call validation. Please, see the diagram for more details. In our diagram A-number is roaming in Operator 1 network, originally belonging to Operator 2, with call going to Operator 3. Call registry of Operator 3 receives a roaming call attempt from Operator 1 and would like to match calling details. It reaches out to CR of operator 2 to confirm roaming status and call details.Operator 2 confirms roaming status and call details to terminating operator. In turn, Operator 3 confirms call details to Operator 1, thus completing call validation between 3 Call Registries. Keep in mind that numeration is purely to guide user through the process. In reality steps are done instantly & asynchronously.