I need to make chatting app that is including voice , video chat.
And also need to integrate facebook.
This app will support single and group chat features.
You might to refer Viber app in playstore.
23 freelance ont fait une offre moyenne de 1084 $ pour ce travail
I will help you in making your application with features that you required plus i will help you in some extra modification like voice recognization of users to fullfil their data and information.