User-to-User information

Hello everyone.
Have anyone worked (deal) with UUI information field in ISUP(ITU) IAM and BSSAP SETUP messages. I'm trying to use these fields to show additional information on the screen of mobile terminal. But it does't works.
Question is: how mobile terminal use these field in setup message?
What recommendations (3gpp or gsm ts or etsi)describe the behavior of the terminal(what feilds it takes and show on screen).
p.s. at the moment i use implicit UUI activation.
Thanks in advice.