title: How to detect user location for RIM / Blackberry using IP address on a website?
body: <p>I run a website which customises content by the user's location at a country level, so that users from different countries see different content. To determine a user's location, we run the IP address presented by the client in the REMOTE_ADDR header against MaxMind.com's GeoIP database. For desktop traffic this generally returns us adequately accurate data.</p>
  
  <p>However, for users browsing from mobile devices, things are different. For example, the same user has come through from a South African IP address on desktop, and a United Kingdom address on his Blackberry. We know that he is physically in South Africa. On investigation, his UK IP address belonged to Research In Motion Limited, which is obviously the UK-based Blackberry service. His web requests on his Blackberry handset must be routed through RIM in the UK.</p>
  
  <p>We've looked through the request headers to see if the actual origin IP address was shown in a header other than REMOTE_ADDR but have not found anything.</p>
  
  <p>Any suggestions?</p>
  
  <p>Many thanks!</p>