application/App.tsx

import React from 'react'
import { AppRegistry, Platform, SafeAreaView, Text } from 'react-native'

function App(): JSX.Element {
	return (
		<SafeAreaView>
			<Text>test</Text>
		</SafeAreaView>
	)
}

export default App

if (Platform.OS === 'android') {
	AppRegistry.registerHeadlessTask(
		'RNCallKeepBackgroundMessage',
		() =>
			({ name, callUUID, handle }) => {
				// Make your call here
				console.log('something')
				return Promise.resolve()
			},
	)
}