How do I send an OTP to certain mobile number I put in Input Field, if I put correct OTP then it should move to the next screen?

Update: Since the documentation to use Firebase along with Unity is really unclear I had to find an alternative. I found the solution. I am using TextLocal as a SMS gateway provider. Here's the tutorial I followed on Youtube: https://www.youtube.com/watch?v=d8OrtnpFC3M&feature=player_embedded

The tutorial is in C# but is not meant for Unity. I modified the code to suit Unity and here's my code:

using System; using System.Collections.Generic; using System.Net; using System.Collections.Specialized; using System.IO; using System.Text; using UnityEngine; using System.Collections.Generic; using System.Net; using System.Collections.Specialized; using System.Threading.Tasks; using System.Linq; using Random = System.Random; using UnityEngine.UI;

public class OTPSMS : MonoBehaviour { // public string txtPhone; // public string txtName; string randomNumber; public GameObject MessageBox; public GameObject MessageBox2; public GameObject MessageBox3; public GameObject MessageBox4; public InputField txtPhone; public InputField txtName; public InputField txtVerOTP;

// Start is called before the first frame update void Start() { MessageBox.SetActive(false); MessageBox2.SetActive(false); MessageBox3.SetActive(false); MessageBox4.SetActive(false); } // Update is called once per frame void Update() { } public void login() { String result; string apiKey = "YOUR API KEY"; //The one which you get on TextLocal after registering . Follow the youtube tutorial string numbers = txtPhone.text; // in a comma seperated list

  string sender = "TXTLCL";
  string name = txtName.text;
  var rnd = new Random();
  randomNumber = (rnd.Next(100000, 999999)).ToString();
  string message = "Hey " +name+ " Your OTP is " +randomNumber ;
  String url = "https://api.textlocal.in/send/?apikey=" + apiKey + "&numbers=" + numbers + "&message=" + message + "&sender=" + sender;
  //refer to parameters to complete correct url string
  StreamWriter myWriter = null;
  HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);
  objRequest.Method = "POST";
  objRequest.ContentLength = Encoding.UTF8.GetByteCount(url);
  objRequest.ContentType = "application/x-www-form-urlencoded";
  try
  {
      myWriter = new StreamWriter(objRequest.GetRequestStream());
      myWriter.Write(url);
  }
  catch (Exception e)
  {
      MessageBox.SetActive(true);
  }
  finally
  {
      myWriter.Close();
  }
  HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();
  using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))
  {
      result = sr.ReadToEnd();
      // Close and clean up the StreamReader
      sr.Close();
  }
  MessageBox2.SetActive(true);

} public void Verify() { if(txtVerOTP.text ==randomNumber) { MessageBox3.SetActive(true); } else { MessageBox4.SetActive(true); } } }

And this is what the UI and hierarchy looks like: