Call Barring is actually part of CLI-based routing and works by looking at the number that is calling you before it is allowed in your telephone system. It will then decide what to do with that call based on a simple rule set that you have previously configured via your online control panel.
You can define which telephone numbers are subject to call barring. You can do this by simply entering the full telephone number or part of a telephone number into a simple rules set on your online Control Panel. For example you may wish to bar a specific number and in this case you would enter the phone number As your telephone sees it… For example 01234567890
Alternatively you could bar a whole range of telephone numbers.For instance, you may wish to bar 0843 numbers as these tend to be used by marketing companies. This would be entered into the system using the following format 0843*. You can also choose to handle withheld numbers in a particular way as previously illustrated.