Private Sub txtnummmer_KeyPress(KeyAscii As Integer)
 
   If InStr("1234567890" & Chr$(8), Chr$(KeyAscii)) = 0 Then
      KeyAscii = 0
   End If
 
End Sub

Private Sub txtnummer_KeyPress(KeyAscii As Integer, index As Integer)
 
   Select Case index
   Case 0
   If InStr("1234567890" & Chr$(8), Chr$(KeyAscii)) = 0 Then
      KeyAscii = 0
   End If
 
   Case 1
   If InStr("1234567890" & Chr$(8), Chr$(KeyAscii)) = 0 Then
     KeyAscii = 0
   End If
   End Select
End Sub