Guys there are many services online where you can create an account, and they give you a number where people can opt in by sending a particular keyword. I would forget about using real phones and sims etc for SMS marketing...make use of these services. When people text your keyword to your number, it works like an autorepsonder. And after the initial message, you can send your "list" any message you want...
On top of this, the company pays you a percentage of the premium fee..
The trick comes in to try and build that list...
A good way may be a twist on the ASDA method mentioned here before...print flyers out saying they can claim a free $200 (ASDA/Wallmart whatever) voucher by texting the KEYWORD to your premium number. Hand the flyers out at ASDA/or wherever stores. When people text the number, they get a message back with a link to a CPA offer (maybe an email submit) to win an ASDA/whatever voucher.
BAM: You just killed three birds with one stone...you get about 40% of the premium SMS charge, you earn CPA commissions when people complete the offer, and you building on your SMS list to market to later!