Hum, ... I just made a fool out of myself :)
The frames for SDCCH/8 show really nothing valid
(looks like random
bytes), things like
09 80 7f 47 49 06 1d 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
That actually looks like SI5
09 00 47 d5 2d 06 1e 00 00 69 7c a0 91 3d 22 ff ab fe
6c 4f 56 4f 36
and that kinda looks like SI6
So maybe the problem might be else where ... time to look into LAPDm ...
Sylvain