Seen on a billboard in London, near Oxford Circus tube.A part electronic animated advert offering a discount at a local store. If you text to 79990 you'll receive a Datamatrix code.
In this case, it's the store which is using the code; they'll scan it in before giving you a discount.
This is a pretty good way of distributing codes. The retailer gets your phone number and, when you show the code they'll get a good idea of what phones are popular so they can work out which accessories to stock. They can probably upsell you a newer mobile if you've got a brick.
I took a quick scan of the code on the advert using Quickmark - sadly, it was only dummy text.
I wonder how long it will be before supermarkets start sending these rather than physical vouchers.