private async void btnSendCode_Click(object sender, EventArgs e) { NumberToSendMessage = tbPhoneNumber.Text; if (string.IsNullOrWhiteSpace(NumberToSendMessage)) { return; } // this is because the contacts in the address come without the "+" prefix var normalizedNumber = NumberToSendMessage.StartsWith("+") ? NumberToSendMessage.Substring(1, NumberToSendMessage.Length - 1) : NumberToSendMessage; client = NewClient(); await client.ConnectAsync(); hash = await client.SendCodeRequestAsync(normalizedNumber); tbPhoneNumber.Enabled = false; btnSendCode.Enabled = false; tbVerficationCode.Enabled = true; btnLoginNew.Enabled = true; }