Dear Bijoy,
Pix is right. It is not a FAILED RACH. In fact it is just a narrow band noise which LOOKS LIKE a RACH attempt and is also successfully decoded and due to this attempt a SDCCH is also allocated for the ‘Ghost MS’. But as it was’t generated by a MS, the SDCCH will eventually be released.
Dear Pix,
Your reply looks more like from a Ghost rather than a Ghost Hunter 🙂