When an advert is on, the response button at the base of the screen lights up. The viewer is able to respond immediately, taking a pro-active decision to find out more. Viewers simply press the illuminated button, and that activates the advertiser's call centre number. Twenty seconds later a potential customer is speaking to a sales agent. This automated connection to your call centre saves the customer from having to dial a phone number or remember an address. It's the immediate translation of interest into action - and over half of viewers say they have acted upon seeing an advert. Campaigns are very accountable. We can use a BT tracking number to monitor call data, allowing you to find out exactly how well your money is being spent.