Authentication Failed: The username or password is incorrect on the device.
Check what the credentials should be by clicking on Users » username » View Devices and then amend the credentials on the mobile device.

Incorrect Calling Number (xxxxxxxxxxx): The user is connecting from a number which does not match the number specified when the device was setup. Check the device details by going to Users » username » View Devices. If the number is incorrect the device needs to be deleted and then recreated using the new number.
 
User not enabled: The user has been disabled by their administrator.
Users can be enabled by going to Users » username » Enable.

Device not enabled: The device has been automatically disabled due to excessive authentication failures. The device will need to be deleted ( Users » username » View Devices » Delete) and then recreated.

User account locked out: The user has been locked out. This will only occur if they are using VPN credentials (i.e. not device-specific credentials) and have had an excessive amount of authentication fail ures. Click on Users » username » Unlock to unlock the user.

Login attempt outside allowed hours: The user is attempting to login during a time which is outside the “allowed times” as configured by their administrator. To modify the allowed times go to Users » username » Network Access Policy » View Access Times