It would probably hinge on the country and carriers you're talking about. For example, I'm in Japan and most carriers have hobbled SMS intentionally. Nobody here 'texts' anyone, we use e-mail. A little more information from you might help.
I want to send out a daily "tip". So I advertise on my site. To get your daily "tip", just text tip to 12345. You will get a daily text with your tip.
I know these services cost the user something like 9.99 a month or whatever. I would like to know where to start. I think the 12345 is called a short code. I pay a company to set everything up and if all goes well, I have 10,000 people paying me $9.99 a month for my daily "tip".