International Call Block does what it says - it prevents international calls from being made from your internet phone.

Visitors to your house or employees at your office would hesitate to make international calls from your traditional phone because it costs so much. But as VoIP is cheap, some people may not think twice before making a phone call to Uncle Frank in London from your internet phone without your leave. After all, what is a few pennies, they tend to think.

To put off such people and not to get charged for international calls you did not make, turn on this feature and no international call would go out from your internet phone.

As this feature is generally turned on and off through your online account manager with your VoIP service provider, other people cannot disable this function unless they know your password.