Hello Dieter,
I anyone has access to a real GSM Abis Interface and can provide traces of a working network this could be very interesting to have a look at.
And for tracing the GSM air inteface with cheap equipment, well, lets hope that we can get something for that in the future...
Couldn't we use a GNU-Radio combined with the GSM-HF-RX? We had a student research project which used that with Wireshark. I think I could borrow it for a few days and sniff some stuff at our lab. Just tell me what sequences you need.
But first I have to write some exams, no hands-on-hardware until they are finished ;-)
Best Regards, Holger
-- | Holger Adams, holger@kernreaktor.org | WWW: http://www.kernreaktor.org