From Forum Nokia Wiki

After reading this and this and this I decided to knock up this dodgy prototype amazing application for S60 v2.x phones (but not v1.x or v3.x). Tap in some Morse code, and then send it as an SMS. Keys are:

• 1, 4, 7, or * - Dot
• 2, 5, 8, or 0 - Space
• 3, 6, 9, or # - Dash
• Left arrow - Dot
• OK key - Space
• Right arrow - Dash
• C key - Delete last dot, dash or letter
• Call/green key - Send as SMS

For a gap between letters, press space once. For a gap between words, press space a second time.

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http://laivakoira.typepad.com/blog/2005/05/morse_texter.html