Hi there,
Understood the requirements. The app would consist from two parts, 1st would be the php web app to use for tracking/signal receiving, and the 2nd part would be the android app which would emit it's location to the web app. The android app would have to be started in order for the web app to be able to show the location of the phone, and it would only work on android phones. I could provide the iOS app as well but I don't have an iOS phone to test it so I may need your help to debug the iOS emitter.
Regards,
Julijan