This is a tool for sending SMS via your mobile phone. In principle, every modern mobile phone should be supported; for a list of tested mobile phones, please visit the KSMS-Tool homepage.
The connection to the mobile phone is established via the serial interface. In principle, every serial emulation (e.g. via USB, IrDA, Bluetooth) should also work if an error-free connection is guaranteed (especially in the wireless cases IrDA resp. Bluetooth).
Details on choosing a non-default connection to the mobile phone or on how to populate the user-defined addressbook can be found on the KSMS-Tool homepage.