Samsung SGH-A197ZKAATT - Manual (Page 31)

Entering Text 27
4. To clear the symbol(s), press the key. When the input
field is empty, this key returns the display to the
previous mode.
5. To insert the symbol(s) into your message, press the OK
soft key or the key.
Using Numbers
Number mode enables you to enter numbers into a text message.
Press the keys corresponding to the digits you want to enter.