I am also developing this kind of application which all about the GPS tracking.
Application should run in background and for every 30mins it should get the Longitude and Latitude values by overriding the previous values these current values should store.
when the user press a button those values should be sent to a server at emergency situations and at the same time application should make a cal to specific number and then the Loud speaker of the mobile should activate.
In this when the GPRS connection is not available then that Message should sent to mobile number instead of server.
Last one Application must have a auto run option. means when the mobile is off it will stop and when we switch on mobile Application should be run automatically.
Please help me in this