Ringless voicemail is a technology that allows a voice message to go directly to a mobile voicemail box without making a call to a phone.
The technology only works with mobile phones. This may sound like a limitation, but in reality it is not.
According to a study conducted by Pew Research in 2013, 91% of the adults in the United States do own cell phones.
There are certain segments of the population that are less likely to own a cell phone than others, such as seniors ages 65 or older, those without college education and those who live in rural areas.
However, even for these segments the ownership is extremely high.
For example, 92% of people living in urban areas own cell phones vs 85% of people living in rural areas. (Source http://www.pewresearch.org/fact-tank/2013/06/06/cell-phone-ownership-hits-91-of-adults/).
This means that ringless voicemail marketing can reach almost any person living in the United States.