USSD Gateway

[nlicina]

Hi,
 I will try to be short. My question is: is it possible to create a simple USSD gateway by using JAIN TCAP API? I've read something about ss7 protocol stack and, if I understood corectly, the main protocols for ussd are TCAP and MAP. The thing that I don't know is: how to extract MAP from TCAP and after that, how to extract  USSD from MAP. I'm familiar with TCAP primitives. It is possible that I understood something wrong, so please,  help... Thanks in advance.