I am trying to send message using signInWithPhoneNumber from firebase but I am getting following error on implementing , I also imported firebase still same issue.

import firebase from 'firebase/app';
import { environment } from 'src/environments/environment';

export class TabPage implements OnInit{
  code: string = '+91';
  spin: boolean = false;
  otpSent:boolean = false;


  recaptchaverifier;
  confirmationResult: firebase.auth.ConfirmationResult;
  phoneNumber: string;
ngOnInit(){
    this.recaptchaverifier = new firebase.auth.RecaptchaVerifier('recaptcha-container');
    this.sendOTP();
  }

sendOTP(){
    var phNo = this.code+'******';

    this.spin = true;
    firebase.auth().signInWithPhoneNumber(phNo,this.recaptchaverifier).then(result=>{
      this.phoneNumber = phNo;
      this.otpSent = true;
      this.confirmationResult = result;
      this.spin = false;
      console.log(result);
    }).catch(err=>{
      this.spin = false;
      alert(err);
    });
  }
}