I installed it last night. After a lot of test managed to get it works on my phone. I am in Argentina, and It is great this application works for me. Mobile Defense is not yet.
I am testing the missing device feature. App install a service that runs in background. I am only guessing, but, I think they send a SMS that trigger the service to send your location coordinates to the server in order to locate your phone.
I think the service is not sending location coordinates all the time, so I guess the app works the way I described.
What do you think? BTW this is a handy application.