There could be a number of reasons why the box refuses or can't connect to servers. First, you need to make sure that the Internet connection is available and it works normally. If the box is connecting through a router, you will need to configure the router to allow access to VOIP services. Also, if there is an active Firewall enabled on the router, you need to create rules for this connection. Another possibility is that the box is only allowed to work on specific countries. Many users encounter this problem: they try to use a piece of hardware which needs to connect to a foreign IP address but that IP address is blocked and such problems may appear.
As you can see, the solution to your problem could be one of the suggestions I mentioned earlier.