GoAutoDial (formerly VicidialNOW) is an open source predictive dialer and inbound IVR/ACD call center system based on CentOS.

We can use this system for voice message broadcasting. you can use this system for advertisement of your brand. You just have to record a message and upload phone numbers list select a recorded message and start. System automatic dial numbers from the list and when some one pick the phone then recorded message will start to play and if any one interested in your product he will call you back for order your product.
This is only one example there are many things which you can do this with this automatic system.

I have already done this project for many organizations and they got many customers and business.