How do I solve the Failure to establish the ISDN link when the router notifies the ISDN-side device that no available B channel exists on the local end

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The router connects to an integrated services digital network (ISDN) through the ISDN-side device. When the router receives a channel identification message from the ISDN-side device and the message contains the option indicating that only the indicated channel is acceptable, if B channel that the ISDN-side device assigns to the router is occupied, the router notifies the ISDN-side device that there is no available B channel on the local end. In this case, the ISDN link fails to be established.

To solve the problem, run the isdn bch-assign command on the router to enable the router to ignore the option indicating that only the indicated channel is acceptable sent from the ISDN-side device.

Other related questions:
How do I view the status of an ISDN link
Run the display isdn call-info command. <Huawei>display isdn call-info Serial1/0/0:15 : Link Layer: TEI = 0, State = MULTIPLE_FRAME_ESTABLISHED Network Layer: 0 connection(s) If the Integrated Services Digital Network (ISDN) link is in the MULTIPLE_FRAME_ESTABLISHED state, the ISDN link is established successfully.

How do I view the duration of an ISDN call
Run the display isdn call-record command. In the command output, the value of Seconds Used is the call duration.

Why ISDN phone is unavailable
The causes are as follows: - The ISDN phone has no power supply. ISDN phones can obtain power by themselves or through the remote PBX. By default, the 2BST (BRA) card does not provide power when the AR router is connected to an ISDN telephone. If power supply is required, run the remote-power enable command. system-view [Huawei] voice [Huawei-voice] port bra 3/0/0 [Huawei-voice-bra3/0/0] remote-power enable - The phone pin assignment is incorrect. The pin assignment of the ISDN phone differs from that of a common network cable. The ISDN crossover cable is often used to connect the AR router to the ISDN phone. If the ISDN phone obtains power supply and the pin assignment is correct but the fault persists, contact Huawei technical support personnel.

Why is an ISDN phone unavailable
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: system-view [Huawei] voice [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.

When configured with a link state protocol, why can the local device not establish neighbor relationship with the peer device
When the local device is configured with a link state protocol, first check the type of the interface on the peer device. -To set the network type for an OSPF interface, run the ospf network-type command. -To set the network type of an IS-IS interface to P2P, run the isis circuit-type p2p command. The network types of the interfaces on both ends of a link must be the same; otherwise, the neighbor relationship cannot be established.

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