Hi!
Quite some time ago (must be 2-3 months ago), I have officially inquired at ip.access about the source code of their wireshark modifications, as per the GNU GPL.
It took them some time, but they eventually responded recently. Today I finally received a CD-ROM with the source code.
I've uploaded it to the OpenBSC wiki, and it is now available from http://openbsc.gnumonks.org/trac/attachment/wiki/nanoBTS/wireshark-1.0.6ipa2...
Had I known earlier that ip.access has actually written a GPL licensed dissector, many hours (rather days/weeks) of reverse engineering time would have been saved.
I have not yet had time to review it thoroughly, though I plan to merge/port the interesting bits of it with my dissectors for A-bis OML and ip.access RSL extensions and eventually submit it to wireshark mainline.
If you use this source code, please don't just simply take it and push it to upstream wireshark, as that would conflict with the patches that we have in openbsc git at the moment.
Have fun with it, Harald