Customers will happily text a keyword to you in return for a cash reward, free item, or coupon. Simply advertise the keyword in your store and let them take the initiative. They’ll get something of value and you’ll get their mobile number.
Instead of making customers search high and low for your Wi-Fi password, or worse, get up and ask you for it, they can instead access your Free WiFi using their mobile number, email address, or Facebook login. It’s a seamless process for you and them.