The reason they call a cellular number or one on the Do Not Call List and hang up on one ring is so that when you follow up and try to call them back,  they can say, "What are you complaining about? You called us."

I missed a call and they didn't leave a message, but I called back blocked and it's a "reward redemption" call. They claim you won a gift card for visiting an undisclosed website... I've answered the calls in the past, but from different numbers.

Unsolicited call.  Left no message.

Called and hung up so quickly, it just appeared on my phone as a missed called without any real chance of answering. No message left.

Called but no message