Design Mobile App for Android and iOS

This is design for chat, audio, video (app to app calls) and to landline/mobile no. We want to have a simple but effective UI (with not a lot of jazzy graphics). This app will be mainly used in enterprises. For iOS as well as Android. Screen 0 3-4 graphics banner that explains the USP/features of app with button at bottom stating "Start app" Screen 1 Name Mobile no Agree to terms and condition (bottom) Login with barcode icon at bottom Screen 2 Enter the 4 digit PIN Timer stating "we will call you in 5.00 mintures" Did not receive PIN ? Resend PIN Screen 3 Enter email address Password or PIN Sign-up button, skip button Screen 4 App initialization screen (kind of processing and loading app) Screen 5 Main screen with menu icon on top left, dialer icon on top right, search icon (list of chats with 2 tabs: Chat and Call (listing all calls), similar to google hangout) Material design with + on bottom right, when clicked shows: new chat, new call, new group Menu Screen 6 Detailed chat screen with audio, video call icons on top right, when clicked on name opens the profile screen Screen 7 Outgoing call screen, incoming call screen Screen 8 Settings screen Screen 9 Contacts Screen with list of all and free contacts Screen 10 Dialer screen with dial button 0,1,2,3,4,5,6,7,8,9 and few other options on the screen Display balance on top right, plus button on bottom right that opens contacts After number is keyed in that show the rate for this call or state that it will be free call Screen 11 Invite by email/SMS screen Screen 12 Share in social media site Note: No of screen increase or decrease by 2 - 3.