twillio voice integration with flutter

I need to integrate with the package
https://github.com/diegogarciar/twilio_voice

or otherwise if deemed necessary.

what would it be:
Just be able to call between two devices
a simple accurate screen of this twillio communication.

What I have already configured in the app:

I've already created my TwiML Apps app
I configured Firebase
I configured fcm
I created my keys API key
I'm generating the accessToken with my Android credential