Now if the OMU is BL that maens you cannot access the BTS from BSC. But even in the case of OMU-BL if we want to lock the BTS through the ZEFS command, the message appears that BTS O&M link is out of order. This means our command is not executed by the BSC. But if you see through ZEEI the status of all BTS/TRX is shown BL-USR. But the reverse is not true.That is you cannot unlock the BTS if OMU-BL.