If you don't want people to know you're calling, you can hide caller ID by blocking your own number on both landlines and smartphones.

From Google Voice, you can block a phone number from ringing on your cellphone with call rules designed to help you filter your incoming calls.

On Android Phones To block a recent number, open your device's default Phone app and tap on the recent calls list---it's the little clock in the top-middle of the screen.

Your phone number cannot be blocked while calling toll-free numbers or emergency services. The temporary way of keeping your mobile number invisible from caller ID is as easy as 1, 2, 3.

Robocalls are a persistent nuisance, but you can block them without changing your number.