This wikiHow teaches you how to hide your Android phone number so it doesn't appear on the caller ID of the person you're calling.
Step

Step 1. Open Settings on Android device
Gear-shaped icon

in the app drawer. You can also access it by swiping down from the top of the screen to bring up the notification bar.
Some cellular service providers do not allow you to hide your phone number. Do a test run by calling someone before you use this setting

Step 2. Scroll down the screen and tap Call Settings
You can find it under the " Device " header.

Step 3. Touch Voice Call

Step 4. Touch Additional Settings

Step 5. Touch Caller ID
This will bring up a pop-up window.

Step 6. Touch Hide number
Now your phone number will not appear in someone else's caller ID when you make a call to that person.