No matter what phone service provider you use, you can place an anonymous call. The caller ID of whoever you are calling will show "Restricted number" or "Unknown caller" when you call him, making it impossible for him to call you back or give out your number. If you need to make a phone call but don't want whoever you're calling to get your number, make it an anonymous phone call.
Press the star button (*) on your phone's keypad.
Press the "6" and "7" buttons on your phone's keypad. Together, this will be "*67."
Enter in the person's phone number with area code and make your anonymous call. For example: *67-123-456-7890.