SMS Gateway with iPhone applications

[jjgraz]

We have an application which is almost complete. One unresolved feature is the SMS Gateway portion. Our app will send messages to users at various times. Because we are a small group with a limited budget we do not prefer to sign up with a SMS Service provider and the amount of SMS messages our app sends may break the budget if we do something like pay for each SMS sent. The question is: Is there a program we may buy for a 1 time fee that can be installed server side and send SMS's forever and free? I have heard about free SMS services which insert little advertisements into the SMS as a way to get a free service. Is that Legit, or has anybody any further ideas on how to minimize these SMS costs?

Thank you, I appreciate it very much.