This program is a clever (just a little):
it will send only one message to the Caller whose number repeats.

This program runs in background completely.
To turn it on/off you will simply have to launch this program again, and check/uncheck Active option.

(The PPC Phone Edition version displays a small icon on the bottom
of the screen, to inform you if it's working).

Try the free trial version (limits: it will reply only three times)
or buy the password to unlock.

No special setup file, just paste the downloaded file
to your mobile device in any folder,
eventually you can make a shortcut.

more details:
www.jgui.net/DND/
Have you any reason
to not pickup the Phone?