I just recently (May 1st) put my own 24/7 internet radio station online. I've recruited nine other hosts thus far, to join me to form a Conservative Talk Radio Network. Our numbers have been modest to this point, as you would expect, but since all the shows I've placed on my network have an established listener base, I'm confident that over time, more and more listeners will find their way to the network.
Believe it or not, I've already brought in significant ad revenue, using the "Pay-Per-Call" model and in my opinion, it makes the most sense for both the radio station and the advertising client.
The premise is really simple. Essentially all of the commercials contain a toll-free number or website address that is unique to your station. You are NOT paid to run their commercials, but you ARE paid anytime a listener calls that toll-free number to request the product or information or when they visit the website and likewise request information or sign-up for a free trial, etc.
The revenue each time that happens can range from $2-$10 or much higher. One of my advertisers pays $70 a pop and there may be others out there that pay more.
Thus far, I've generated $217 in just two weeks, which is great. I'm sure it won't be like this all the time, especially in this early stage of building an audience, but once things get to where I hope to be, I'm confident the revenue should be enough to not only cover expenses, but make a small, but significant profit.
The trick is of course to convince the reps that handle this type of advertising to take a chance on you, but in a way, they have nothing to lose. If no one listens and no one calls, then they aren't really out anything. Your listeners must act in order for you to generate any revenue. It's good for them and it's good for you and even if your audience is relatively small, you still might do well enough, with the right products for your station to at least break even.