Google AdWords now have call metrics where they give you a unique 0800 number and charge you £1 for every call that goes over 30 seconds. It's a great way of measuring campaign effectiveness and roi. I want to do similar for my seo campaigns. Any ideas of how i can do this in the UK for a reasonable price? My guess is that i would need a telephone line that i can add call extensions to which then redirects to clients telephone numbers but where i can get this done cheaply is the biggest question. Any ideas?