OK. We were looking on a wrong documentation, a bit. As far as we use AT commands, we need GSM 07.07 - Main AT commands and Annex A from GSM 07.05 - Additional AT commands (SMS and CBS). Can be downloaded from http://wiki.openmoko.org/wiki/GSM#GS...in_AT_commands I didn't understood how decoding should be done correctly and where did we made mistakes, but now I know how to check, if user has left ussd menu.