The cash cow that is internet search advertising has prompted America Online to further expand its technological horizons.

AOL, the biggest stateside internet provider, has departed from the usual revenue model whereby advertisers pay only when someone clicks on their ad, in favour of charging advertisers according to the number of telephone calls generated by a given message.

The ISP has also improved its search functions, making them more geography and topic specific, working with Norwegian company Fast Search & Transfer to achieve its aim.

Until now AOL, with 22 million US subscribers, has relied on a partnership with Google to provide most of its search results. During the first nine months of 2004, AOL generated $219 million (€168m, £116m) advertising revenue, mostly from Google.

Says a conciliatory Gerry Campbell, vp and general manager of AOL Search: "We're not stepping away from Google in any way. We're just continuing down our path toward our vision of what search should be, which is a little bit different than Google's."

Data sourced from Wall Street Journal Online; additional content by WARC staff