Call processing system

1. A call processing system for handling a call comprising:

a signaling interface configured to receive an initial address message from a mobile carrier switch wherein the initial address message comprises a plurality of fields; and

a processing system configured to process the initial address message to determine if a field of the plurality of fields of the initial address message is populated and populate the field if the field is not populated, resulting in a modified initial address message; and

the signaling interface further configured to transmit the modified initial address message to a routing system.

2. The call processing system of claim 1 wherein the routing system comprises a switch of a public switched telephone network (PSTN).

3. The call processing system of claim 2 wherein the switch comprises a class 4 switch.

4. The call processing system of claim 1 wherein the field comprises a charge number field and the charge number field is populated with a pseudo charge number.

5. The call processing system of claim 4 wherein the routing system is configured to receive the modified initial address message and allow the call based on the pseudo charge number.

6. The call processing system of claim 1 wherein the field comprises an originating line identification field and the originating line identification field is populated with pseudo originating line identification number.

7. The call processing system of claim 6 wherein the routing system is configured to receive the modified initial address message and allow the call based on the pseudo originating line identification number.

8. The call processing system of claim 1 wherein the call processing system comprises a service control point (SCP).

9. A method of operating a communication system, the method comprising:

receiving an initial address message into a call processing system from a mobile carrier switch wherein the initial address message comprises a plurality of fields;

processing the initial address message to determine if a field of the plurality of fields of the initial address message is populated;

populating the initial address message if the field is not populated, resulting in a modified initial address message; and

transmitting the modified initial address message to a routing system.

10. The method of claim 9 wherein the routing system is configured to transmit the initial address message to the call processing system in response to receiving the initial address message from the mobile carrier switch.

11. The method of claim 9 wherein the routing system comprises a switch of the public switched telephone network (PSTN).

12. The method of claim 11 wherein the switch comprises a class 4 switch.

13. The method of claim 9 wherein the field comprises a charge number field.

14. The method of claim 13 wherein the charge number field is populated with a pseudo charge number and wherein the call is allowed based on the pseudo charge number.

15. The method of claim 9 wherein the field comprises an originating line identification field.

16. The method of claim 15 wherein the originating line identification field is populated with a pseudo originating line identification number and wherein the call is allowed based on the pseudo originating line identification number.

17. A non-transitory computer readable medium having program instructions stored thereon for operating a call processing system that, when executed by the call processing system, direct the call processing system to:

receive an initial address message wherein the initial address message comprises a plurality of fields;

process the initial address message to determine if a field of the plurality of fields of the initial address message is populated and populate the field if the field is not populated, resulting in a modified initial address message; and

transmit the modified initial address message.