${HANGUPCAUSE} always 0 on pri

Strange problem with a PRI and a TE210P, in awlays seeing a hangupcause of 0, D channel debug as follows.

< Protocol Discriminator: Q.931 (8) len=14
< Call Ref: len= 2 (reference 7/0x7) (Terminator)
< Message type: DISCONNECT (69)
< [08 03 04 80 81]
< Cause (len= 5) [ Ext: 0 Coding: CCITT (ITU) standard (0) 0: 0 Location: Public network serving the remote user (4)
< Ext: 1 Cause: (null) (0), class = Normal Event (0) ]
< Cause data 1: 81 (129)
< [1e 02 82 88]

strange thing is, on a nortel meridian on the same line, im seeing the correct cause in the d channl messages. ANyone have a clue, it’s a euro isdn PRI. It would be nice to give people the correct signal ather than just busy.