Mobile-to-mobile call determination

1. A system comprising:

a Service Control Function (SCF) node including a processor and executable instructions configured to be operated by the processor to determine whether a call is a mobile-to-mobile call between subscribers of a telecommunication service provider by:

sending a subscriber state request specifying an identifier of a serving subscriber of the call to a Signaling System Number 7 (SS7) network, and

determining that the call is a mobile-to-mobile call if a response to the subscriber state request indicates success; and

a Signaling Transfer Point (STP) node of the SS7 network including a processor and executable instructions configured to be operated by the processor to:

determine whether the serving subscriber identifier is included in a routing database of the STP node,

in response to determining that the serving subscriber identifier is included in the routing database, communicating with a relay function and responding to the subscriber state request with a default state indicated by the relay function, the relay function being used in place of a subscriber database of the telecommunication service provider, and

in response to determining that the serving subscriber identifier is not included in the routing database, responding to the subscriber state request with an error message.

2. The system of claim 1 , wherein the relay function is a Mobile Application Part (MAP) signaling relay function of the system that receives requests from the STP node and provides the default subscriber state in answer to the requests.

3. The system of claim 1 , wherein the serving subscriber identifier is a Mobile Subscriber Integrated Services Digital Network (MSISDN) number.

4. A method comprising:

receiving, by a node of an interconnecting network, a request specifying an identifier of a serving subscriber of a call;

determining, by the node, whether the serving subscriber identifier is included in a routing database of the node;

in response to determining that the serving subscriber identifier is not included in the routing database, responding to the request with an error message; and

in response to determining that the serving subscriber identifier is included in the routing database, communicating with a relay function and responding to the request with a state indicated by the relay function, the relay function being used in place of a subscriber database and the state indicated by the relay function enabling a call type determination for the call.

5. The method of claim 4 , wherein the error message enables a determination that the call is not a mobile-to-mobile call.

6. The method of claim 4 , wherein communicating with the relay function comprises sending the request to the relay function and receiving a response from the relay function.

7. The method of claim 6 , wherein the responding to the request with the state indicated by the relay function comprises sending the response from the relay function as the response to the request.

8. The method of claim 6 , wherein the relay function is a Mobile Application Part (MAP) signaling relay function that receives requests and provides a default state in answer to the requests.

9. The method of claim 4 , wherein the node is a Signaling Transfer Point (STP) and the interconnecting network is a Signaling System Number 7 (SS7) network.

10. The method of claim 4 , wherein the subscriber database includes home location registers (HLR) and visitor location registers (VLR) of a telecommunication service provider and the routing database maps subscribers of the telecommunication service provider to the HLRs.

11. The method of claim 4 , wherein the request is a MAP Any Time Interrogation (MAP ATI) request received from an intelligent node.

12. The method of claim 11 , wherein the intelligent node determines the call type based on the response received from the node.

13. The method of claim 12 , wherein the intelligent node conditionally reserves funds at a charging system based on whether the call is determined to be a mobile-to-mobile call.

14. A method comprising:

sending, by an intelligent node, an Electronic Number (ENUM) query specifying an identifier of a serving subscriber of a call;

receiving, in response, by the intelligent node, an identifier of a telecommunication service provider associated with the serving subscriber; and

determining, by the intelligent node, whether the call is a mobile-to-mobile call based at least in part on the telecommunication service provider identifier.

15. The method of claim 14 , wherein the intelligent node is a service control function (SCF) node.

16. The method of claim 14 , wherein the intelligent node sends the ENUM query in place of a request to a Signaling System Number 7 (SS7) network for a subscriber state.

17. The method of claim 14 , wherein the ENUM query is directed to an ENUM routing function of a telecommunication service provider.

18. The method of claim 17 , wherein the ENUM routing function is associated with a database mapping telecommunication subscriber identifiers to telecommunication service provider identifiers.

19. The method of claim 18 , wherein the determining comprises determining whether the telecommunication service provider identifier included in the response is associated with a calling party of the call.

20. The method of claim 14 , further comprising conditionally reserves funds at a charging system based on whether the call is determined to be a mobile-to-mobile call.