Question regarding USSDC

[aparajith]

1. Path of travel of a USSD message is
Mobile Phone -> MSC->VLR -> HLR->USSDC---> How does it reach the external network ?
2. Does the connection to the the Internet does it use TCP/IP ?
3. How is a USSDC identified from internet ?
4. What part of the USSD command ( say *100*2004# where 100 means Account query application and 2004 is the account number) is routed from the USSDC if USSDC knows that the request is for an application that is running in the internet ?
5. Does USSD command can have alphabets like *st*ORCL# ?

Thanks in advance

[vinaypatodia]

1. A USSD gateway like NAMP is required, which can route request/response to/from a url on the net.
2. same as above.
3. same as above.
4. same as above.
5. No most phone does not allow to initiate a USSD connection with alphanumeric string. But later in session, you can input alphanumeric data from the phone.