Palm Tungsten W - Manual (Page 339)

Mobile preferences
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To enable or disable call waiting:
1. Tap Call Settings.
2. Tap the Enable call waiting check box to select or deselect it.
3. Press Function + Enter , or tap OK.
Concealing your number
You can conceal (block) or display your number when making a call.
To conceal or display your number:
1. Tap Call Settings.
2. Tap the Conceal my number when making a call check box.
Tap Call Settings
Tap check box
Tap Call Settings