Was problem with NDDI boards. Solution was - External services/ trunk COS - item "Unavailable Time Betw.2 Seizes" value 10 (1 sec) was changed to 20 or 25 (with board reset).
Attempt an other NDDI 2 board.
If you have a occurences about NDDI 2 board.
Chase bunches and adaptability to your phone number. chase bunches give planned occupies.