Hello,
We have gone through your requirement. Based on that, we have some initial points as below:
1) We need to add some third party chat server (like XMPP, quickblox) to achieve our chat application. If you have decided to use any other, then feel free to share with us.
2) You need to purchase these 3rd party api for Voice message, share file, etc.
3) Regarding appcelerator: We are not recommended this Titanium framework, as this is cross platform. But to achieve all these feature, there might be some limitation. Also other 3rd party chat server may not fully support this appcelerator.
4) So we will develop the app in native for iOS, Android with help of chat server and also need to create our admin panel if required.
Kindly have a look at above and let us share your views.
Thank you.