There are lots of so-called "free" internet service providers, My Dialup is one of them, see a list here:
http://www.freebielist.com/isp.htm"Free" in this context only means that to enable internet use you don't have to have a contract for a fixed period. Otherwise the service is not free, you pay for the cost of an 0845 or 0844 call, that is the way they make their money. For this reason it is unlikely that an underlying geographic number can be found for these internet service providers, otherwise they would provide a genuinely free service and would go bust.