When the voice service is configured through the CLI, the system prompts that the MG interface fails. Which of the following are possible causes?

If a rogue ONU exists on a PON port of the OLT and has gone online, another ONT or all ONTs connected to the same PON port may go offline or go online and offline frequently.

Max-Forwards fields can be used in S1P messages to solve loop problems and avoid endless packet forwarding.

(Radio) When using the siP protocol, you need to use a local number graph for matching, if you use the default matching mode to match a 7-digit number beginning with 7727, then the following options are available?
The figure is

In Huawei's u2000 management system, when adding network elements, you can only add -- ones- when you access the network element.