The first hurdle is to make them active after joining, i.e., when they starts logging in everyday and gain knowledge on SFI basics. Then send regular mail and ask them to call you or put their mobile number in profile so that you can call them. This is the one way.
Another way is to send them friend request in Facebook. If they accepts, then send message to them if they are offline. If they are online, then starts chatting. Your task will be easy
