We started working with Casa Brasil a number of years ago assisting them with some web development on their existing website. We developed a stand alone solution that delivers digital birthday vouchers by email to their customers automatically and this was embedded into their website.
The customer receives a voucher annually just before their birthday which contains a unique QR code. They can then bring this into the restaurant where a member of staff can use their own mobile device to scan the QR code using nothing more than a mobile phone or tablet, and then verify its authenticity at which point the voucher has been used and cannot be used again.
Along with email and voucher verification on mobile devices, the client is also able to track voucher usage.