Is SMS a viable business idea?

As I move into the new year I find myself evaluating different aspects of my life, and the financial aspect of my life is really gaining solid attention. I am ready to finally build some degree of financial freedom, or at least a solid foundation and stability. This has me searching for ideas that can help me get to my goal as quickly as possible. One idea I have been giving serious consideration is an internet marketing company for local businesses.

I have seriously been thinking about starting with providing SMS marketing services. From here I believe I could easily expand into other types of marketing and even build websites eventually. I would begin with the SMS, move into building Facebook and Twitter accounts for people, provide increased local search marketing, and other services.

I was looking for more information about how to go about doing this. I ended up on Wikipedia eventually. I found this page http://en.wikipedia.org/wiki/Mobile_marketing , the free encyclopedia which offered a few different ideas about mobile marketing and SMS marketing, but it didn't cover enough information to help me understand what I am really getting into.

I found several platforms online which provide a variety of services. I am not positive I understand the exact pricing of the services though. If I understand this properly, I need to pay a company a fee each month for messages sent, as well as a monthly fee to another website to actually have a network?

My real concern is in relation to the legal side of things. Are there laws about mobile marketing that I should be aware of? If someone agrees to opt in, and I am able to provide methods for them to opt in, do I really have to worry about this? I know I hear local radio stations advertising contests to get people to sign up for a SMS marketing campaign.

Do any of you have any experience in building a business by offering text message marketing to local businesses? Are there things I should know about before I get started? Do you have any advice that would help me build my business as quickly as possible?