Please see:
Tips for owners:
http://www.lostdogsflorida.org/important-microchip-tips-for-pet-owners.html
Tips to track down an unregistered or "dead end" microchip:
http://www.lostdogsflorida.org/tracking-an-unregistered-or-dead-end-microchip.html
Tips for shelters and vet clinics:
http://www.lostdogsflorida.org/microchip-info-for-shelters-and-vet-clinics.html
Lost Dogs Florida is a 501c3 non-profit EIN# 84-3438237