i have a system that can send sms when setting a schedule to confirm their scheduled appointment, but there's an error +CMS ERROR : 305
'SMS
query = "SELECT * FROM schedule WHERE Phone_Number ='" & txtPhoneNumber.Text & "'"
cmd = New MySqlCommand(query, MySqlConn)
reader = cmd.ExecuteReader
'TIME DATE SMS
Dim date1, time1 As String
date1 = Val(frmViewSchedule.dtpDate.Text)
time1 = Val(frmViewSchedule.dtpTime.Text)
txtMessage.Text = sys_msg + "TIME: " + time1 + " DATE: " + date1
If reader.HasRows Then
reader.Read()
txtPhoneNumber.Text = reader.Item("Phone_Number")
With SerialPort1
.Write("at" & vbCrLf)
Threading.Thread.Sleep(1000)
.Write("at+cmgf=1" & vbCrLf)
Threading.Thread.Sleep(1000)
.Write("at+cmgs=" & Chr(34) & txtPhoneNumber.Text & Chr(34) & vbCrLf)
.Write(txtMessage.Text & Chr(26))
Threading.Thread.Sleep(1000)
MsgBox(rcvdata.ToString)
End With
End If