Most telephone operators provide a caller identity (Caller-ID) service that delivers the telephone number of the person who is calling you along with their call. If the telephone has a display screen you can then see who is calling you before you pick up (you are probably familiar with this sort of service from your mobile phone).
If you don’t have the Caller-ID service turned on then trueCall will still work and filter your calls, but because it can’t identify your callers it will intercept everyone and ask to them to identify themselves each time they call. To get the full benefit from trueCall we recommend that you turn on the Caller-ID service for your line.
The Caller-ID service is free from many network operators – TalkTalk, Sky, Post Office Home Phone, and BT (if you have an annual contract). Virgin Media charge £2.25 per month for the service and BT charge £1.75 per month if you don’t have an annual contract.