React Native Phone call

import React from 'react';

import { Button, View , Linking, SMS,  Permissions,  StyleSheet} from 'react-native';

export default class App extends React.Component {

  render() {

    return (

      <View style={StyleSheet.container}>

        <Button title="phone" onPress={this.btnPhoneClicked} />

        <Button title="SMS" onPress={this.btnSMSClicked} />

      </View>

    );

  }

  askLKermissionsAsync = async () => {

    await Permissions.askAsync(Permissions.Linking);

  };

  askSMSPermissionsAsync = async () => {

    await Permissions.askAsync(Permissions.SMS);

  };

  btnPhoneClicked = async () => {

    this.askLKermissionsAsync();

    let result = await Linking.openURL('tel:');

  };

  btnSMSClicked = async () => {

    //await this.askLKermissionsAsync();

    //let result = await Linking.openURL('sms:');

    await this.askSMSPermissionsAsync();

    let result = await SMS.sendSMSAsync([''], '');

  };

}

const styles = StyleSheet.create({

  container:{

    flex:1

  }

})