Simply, don't - stay well clear. Sending to non opt-in data is not only spam, but a total waste of your time and money.
Even if you purchase data that is opt-in via 3rd party (as in "contact me about similar products and services") it is highly dubious.
It is not hard to build your own opt in lists. Simply add a form to your website, collect numbers using paper forms at your point of sales, and of course print SMS text shortcodes and SMS-QR codes on all your marketing touchpoints and if you make the call to action compelling you will soon grow a list.
For example, in a takeaway print "Join our VIP club, text FOOD to xxxxx" on the window, on the food box, on your flyers, on the receipts - everywhere! In time you will get a list of people who have chosen to receive messages from you. Effectively an SMS text "fan club" for your business. You then pay around 3p per message to communicate with them, instantly at any time. Ensuring you include an optout path so they can leave your list.
If anyone wants a free shortcode keyword, free award winning mobile communications tool and 100 free texts to play with... or a chat about how to perform text message marketing properly (we work with over 90,000 UK businesses, services and community group - so we have more than a little experience) please PM me any time..
Thanks.