Write an Android application

Hi all. For ur first insight we need a complete system for Mobile dialer. just like Itel company([login to view URL]) , Mosip ([login to view URL] ),Mtel dialer.([login to view URL]). So any one who have knowledge of voip can understand easily what we need. moreover unlike others we first want to focus on Android App. 1. Android app for any androip cell Phones. 2. Linux server . where the main application setup files will exists. with which the android application will work and this linux server have full management ..(where we can add different clients voip server public Ips. And each of those public ips will have restriction of calls which will pass on through Linux system like 100, 200, and so on. 3. Vpn OR Byte Saver. will need this server that will also a linux server and will be utilized to bypass voice ports blockage . The first Linux server, The ByteSaver/Vpn server and the end user who have the android app in his/her mobile will all work to gather.. and integrated with each other. 4. The Voip server ( which we not need) but these are the voip servers which public ips we will add..on our Linux server. The actual end user authentication will relates to this server. This VoipServer Public ip will be in trusted in our check list of the Linux server with the managment to add/modify or delete that Voip server Public ip. and again with a check of how many calls will pass on of any particular VoipServer Through our Linux Server.. so if have any question plz update