An ISDN phone may be unavailable because of the following reasons:
The ISDN phone power is not supplied properly.
An ISDN phone's power can be supplied by itself or using the remote PBX. By default, no power is supplied to the AR's 2BST (BRA) board connecting to the ISDN phone. To supply power to the 2BST (BRA) board, run the remote-power command. The detailed configuration is as follows:
[Huawei-voice] port bra 3/0/0
[Huawei-voice-bra3/0/0] remote-power enable
The cable sequence is incorrect.
In most cases, ISDN crossover cables are used to connect the AR and an ISDN phone.
If the fault persists, contact Huawei technical support personnel.