Do you sometimes hope that when you call someone, they won't pick up? You can leave someone a voice message without their phone ever ringing. They won't know and won't have any idea why their phone didn't ring; they will just think they aren't getting service.
Use a service called Slydial. Call 267-SLYDIAL (267-759-3425) from any cellular or landline phone. The service is free; you will just need to listen to a very short advertisement. If you don’t want to listen to the ad, you can pay for the service by purchasing the premium service for a monthly or yearly fee or paying 10 cents for each call you make.
When prompted by Slydial, enter the cell phone number of the person you want to call. The phone number must be a U.S. cell phone number. While you can call from a landline, the number you are calling can not be a landline. Leave a voicemail message when you hear the voicemail greeting of the person you are calling.
Use a service called Bluff My Call. This is a very similar service to Slydial but you will need to sign up and create an account. You can purchase credits, which translate to phone minutes, or buy unlimited monthly subscriptions.