Instant SMS Sender is a freeware software for Windows Mobile 2003 and 5.0 based Pocket PC mobile devices (non-Phone Edition) which integrates with Pocket Outlook and allows you to send SMS through your Nokia/Sony Ericsson cell phone via Bluetooth.

Main features of this application are:

-Supports international characters;
-Contact lookup when a new message arrived;
-Supports Delivery report Notification;
-Integrated with Pocket Outlook.
-Sent and received messages are stored in the Outlook folders.
-Supports sending long SMS messages;

The limitation of the freeware is that outgoing message length is limited to 20 characters.

Download
WM 5.0 version here
WM 2003 version here