Support for Flexi BTS

hi, we managed to run a nokia flexi bts with openbsc. the bts type is "nokia-site". on channel request, the bts nacks the channel activation with cause 0x65 (protocol error, optional information element). by removing the Channel Identification IE from the channel activation message, everything worked, so we assume that this IE causes this error. we tried to modify it: - no zero-length Mobile Allocation included in Channel Identification IE - TLV instead of TV for Channel Description in Channel Identification IE - Channel Description in Channel Identification IE with type 0x62 instead of 0x64 all of these modifications result in the same error. so we came to the conclusion to remove the Channel Identification IE, since it is not really required. attached is the preview patch. does anyone have ABIS traces of a real network, to check how the IE is encoded there? is there any way to get more information from nokia bts why it rejects the channel when using this IE? regards, andreas