SMS spam is never a good idea. Not only is it illegal and people hate it, but it also comes across as creepy. I mean, how would you respond if you got a spam text from someone you did not know? You have the right idea about getting targeted numbers, but you should not go about it like this. Try getting a domain and creating a lead capture page where you get the persons name, cell phone number, cell phone provider, and (or) email address. When they do this, then direct them to a free gift, like an eBook of their choice.