The company holds a database of around fifteen million numbers and there are two ways of accessing a search, each costing £1. It's interesting to note how they amassed these numbers and intend to keep them by not giving the number over to the person making the request. click here
Privacy considerations are mentioned in the linked story and I'm suspicious that their database could be enlarged further using a caller display facility. They'd obviously need more info on the caller to use it, but a secondary database could be slowly built up if the directory is successful. TC.