Code:
Private Sub txtTel_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtTel.KeyDown
If e.KeyCode = Keys.D0 Or e.KeyCode = Keys.D1 Or e.KeyCode = Keys.D2 Or e.KeyCode = Keys.D3 Or _
          e.KeyCode = Keys.D4 Or e.KeyCode = Keys.D5 Or e.KeyCode = Keys.D6 Or e.KeyCode = Keys.D7 Or _
          e.KeyCode = Keys.D8 Or e.KeyCode = Keys.D9 Or e.KeyCode = Keys.Back Then
   lbltelephone.Text = ""
Else
   e.SuppressKeyPress = True
   lbltelephone.Text = "No"
End If
If e.KeyCode = Keys.Escape Then
   txtTel.Text = ""
End If
If e.KeyData = Keys.Return Then
   txtPerson.Focus()
End If
End Sub