I use this script to send SMS from KAddressbook, but can work alone.

Simply feed it with a valid number and a file and it will send it through Gammu

Can send flash messages and ask for return information (look for local bills).

It make some validation of input (void message, unicode) and report errors/success via good looking kdialog.

Depends on:
*) bash
*) gammu
*) coreutils
*) kdialog

Features:
*) easy integrate in kaddressbook
"sendsms.sh -n %N -f %F"
*) easy debugging (set debug=1 in the script)
*) can send long messages
*) unicode support
*) can send flash messages
*) can ask report on delivery

Installation:
copy in search path and make it executable.

Future plans:
*) better command line handling (thanks Shelldorado!!!)
*) phone number validation (working on)
*) make it dialog style indipendant (gnome/dialog/kde/other)
*) easy applet for the desktop (write&send!)
*) send same message to multiple numbers
*) log (success/failure) for complete automation