Page redirect determined by user location

I have a website that need to open a frame determined by the users ip location information the main site has osclass script running in a window. when the page loads it needs to determine the users location and open a location determined osclass script. If I click on the home page the programming needs to identify the user location and open the right classified listings. I have 12 regions that are identified by city name and zip code If the user is not in a region that is identified the main page loads the state wide classifieds. If the state wide classifieds is the loaded option it needs to have access to all sql databases in the state for search function. The region search functions are carried out by osclass sql database for the region and all regions have databases separate from one another