VTO cannot call VTH

• A1:

1. When we use platform, we need to ensure that the device is registered online via the number obtained on the platform.
2. If it is in stand-alone environment, we need to ensure that the configuration is correct----check all the numbers of the rooms(both main and extension) and the VTOs. Note that the registration password is 123456(by default), and the IP address in the VTO management is the actual one, not 127.0.0.1, and check if all the device are online in the status.
3. Check whether the network cables are all cat5e.