how to check a phone number if register at whatsapp ??(Easy Code)

string[] s = { "Phone Number1" ,"Phone Number2"};

                        WhatSocket.Instance.SendSync(s);
/ /Declare Delegate Event
                       WhatSocket.Instance.OnGetSyncResult += Instance_OnGetSyncResult;

//Delegate Event

 void Instance_OnGetSyncResult(int index, string sid, Dictionary<string, string> existingUsers, string[] failedNumbers)
        {
            foreach (KeyValuePair<string, string> iteam in existingUsers)
            {
                MessageBox.Show("existing" + iteam.Key + iteam.Value);
            }
            foreach (string item in failedNumbers)
            {
                MessageBox.Show("not existing" + item);
            };
        }