Thank you Elaji, I am not proeficient in java, I am newbie in ussd gw, I was not able to find good documentation in ussd gw docs about how push is supposed to work, just a brief description.
I try to do my best, but if anyone know a working example (push and pull) or a diagram that help me to understand how push works will be welcome.
About push I understand the following:
1. An external application trigger ussd gw
2. ussd gw call a pre configured http application in order to get message to user.
3. ussd gw send message to user (HLR, then mobile)
4. Mobile handset receives and interaction begins
Is right?