When trying to login in outside the office, this error message will appear if the user is not flagged to login in from a remote location:

'You are not allowed to log in from an unsecure zone. Please contact your administrator' 

This can be changed from your user account by your superuser. The user can be flagged with: 
'Allow login from remote location'

When this is turned on, the user will receive a one time password by either SMS or Email. 
The user can change this option in the login screen if by SMS is preferred instead of by email.

If the user has a static IP address, it is possible register this in the system and the user will be able to login without the one-time-password.