What features are included with the free barring service?

This is a free service which allows the customer to block all incoming calls, without specifying a number to block or a country.

Call Barring Service
How can I subscribe the Call barring service?
What features are included with the chargeable barring service?
Is the Call Barring service free?
How is the Calls Barring Service different from what I already have on my device?
What is the Call Barring service?
How can I manage the Call Barring service (add and remove countries and numbers)?