I'm interested in being able to send out external calls via PHP or another programming language with a prerecorded message (media file). Exactly like PrankDial.com does (minus the pranking).
I need to know what is required to be able to initiate calls from a computer, not using any existing phone lines or phone service? Would I have to pay a gateway or is there a server I can setup, etc? There won't be many calls sent out, and they will be under 1 minute.
I want the most cost-effective way in the long-run.