Last week, VideoEgg launched its AdFrames Brand Response Network, a programme that allows advertisers to buy online inventory based on engagement, rather than impression. Under the system, advertisers negotiate a price for engagement.
To date, advertisers have generally bought online inventory based on a cost-per-thousand basis - spending a set amount per thousand views. However, VideoEgg claims such an approach lacks accountability and forces risk onto advertisers to determine ad effectiveness.
While Microsoft was announced as the first US client for the service, O2 is thought to be the first company to implement the technology in the UK.
Advertisers will now be charged after a user clicks through to certain stages of a site, rather than on an initial visit.
Troy Young, marketing officer at VideoEgg, said advertisers needed to move beyond "the metrics of eyeballs" and evolve from focusing on the quantity of online visitors and on to how long visitors spend on websites.