FLUTTER/ React APP for IOS and Android

The Project Under Discussion Covers The development of a mobile application capable of VoIP / SIP authenticator and applicator to make and receive calls.
Including the following.
• Dialing Calls From the Server against the logged-in user account.
• Recioeve calls For the same account.
• Call logs (Locally Saved in phone Cache / SQL lite)
Technical Details:
We will be creating a Cross-platform App that will be split into IOS and Android versions and will be supported on all Major releases of the OS.
Particular Details
Platform For Development Flutter AND/OR React Native
Core Language Dart For flutter and JS For React Native
Temporary Storage Phone Cache / Local SQL Lite
Long term storage Google Firebase DB
Session Limitations User Defined From Server
Backend Services Existing Linux Servers

Working Details:
On either platform working and functionalities, Will be Identical,
The application can make and receive calls Only with reference to the User logged in.