Simple Android call and messages list app

I need simple application that will be installed on Android device. The application is supposed to sync in background all messages and call list to a MySQL database over 3G/4G/WiFi in realtime. I do not want to store database login information on the device so syncing to a database should be made with PHP script on the server side. I want to store information about: - text messages - SMS (date and time, phone number, direction - sent or received message, and content of the message) - call list (date and time, phone number, direction - outgoing or incoming call) - current call - when there's incoming call there should be information sent RIGHT AWAY to the database that there's incoming call. When the call is finished the record should be deleted. So the best structure of MySQL database will consist of 3 tables: - messages: id (autoincremental), phone_from, phone_to, timestamp, content - calls: id (autoincremental), phone_from, phone_to, timestamp, call duration (0 or -1 for missed call) - current_call: id (autoincremental), phone_from, phone_to, timestamp Checking phone number of the device is required, because I'm not sure if there won't be more than one Android device used. Authentication to a PHP script may be simple by some hashed string or so. If freelancers has any suggestions regarding database structure I'm open for any.