Depending on configuration settings it does the following things:
- Send an SMS message to the caller (configurable contents), possibly containing also the end time of current appointment (configurable).
- Adds an item to calendar (containing the caller info).

Starting from version 1.3 a version for Windows Mobile Standard version (= Smartphone) is also available here or here (mirror). I haven't had a chance to try it out on a real device, so there might be issues. Please report them via the issue tracker here on codeplex.

Installation:
Just get the .CAB file from releases to your device and run it. It will run the setup and you should be all set.

Update Description:
v1.3 (21-12-2007):
- Windows Mobile 6 Standard (aka Smartphone) is now supported.
- A bug introduced by Windows Mobile 6 that calendar appointments were a few hours off should now be fixed.
- Added shortcut to Startup folder to the setup packages, it should now autostart when device is restarted.

v1.2:
- Saving of config still had a bug, now it should work.

v1.1:
- Configuration is automatically saved whenever the user makes any changes. The configuration is stored in \Application Data\SMSNotifierSettings.xml.
- Corrected a bug where an SMS was sent erratically when "missed call count" decreases.
- Menus eliminated (no Quit anymore, use the minimize-button on the top right corner to hide the app when done with the settings).
- Version number added to the About tab.

v1.0:
- Initial release.