1) View the Subrack No., Slot No., and Port No. in the alarm location information.
2) Use one of the following modes to query the loopback status of the E1/T1 port.
GUI mode:
a. On the LMT, select the faulty BTS on the Management Tree tab page.
b. In the Site Description area on the Site Device Panel tab page, view the subrack No., slot No., and port No. of the Abis interface board that is connected to the BTS.
c. Choose BSC Maintenance > Maintain Transmission and Signaling > Interface Board Port Loopback.
d. In the displayed dialog box, set the parameters in the Port Location area and then click Query.
e. Check whether the Loopback Status of the port is No Loopback.
Y => The Loopback Status of the port is No Loopback. The E1/T1 port is not looped.
N => The Loopback Status of the port is not No Loopback. The E1/T1 port is being looped.
f. Check whether the Loopback Mode of the port is Local Loopback or Payload Loopback.
Y => The Loopback Mode of the port is Local Loopback or Payload Loopback. The local loopback or payload loopback is being performed on the E1/T1 port.
N => The Loopback Mode of the port is not Local Loopback or Payload Loopback. The local loopback or payload loopback is not being performed on the E1/T1 port.
MML mode:
Run the MML command DSP E1T1 to view the result.