USSD has a wide and diversified implementation across the globe. Availability of USSD common short code is a country specific phenomena. If you have limited number of telecom operators and a mature telecom regulatory body in your country, then availing services over USSD can be quite interesting over cellular network.
Implementation of USSD service varies from operator to operator. It can be either implement over http and/or SMPP. There is no generic way to connect USSD gateway. However, we always prefer to implement USSD over SMPP protocol and necessary information can be passed using TLV parameters.
Get in touch with our business team for your implementation. Write to us at info =at= hexwireless.com or call us at 02656708585
Note: USSD implementation can put a big hole in your pocket, so think about USSD if you have a fat budget.