RALPH ANDERL, THE founder of high-end eyeglass brand IC! Berlin, stamps his cellphone number on the inside of every frame his company makes to allow any customer to get in direct contact over an issue with their glasses. Every business owner claims to stand by their products, but it’s rare for one to make him or herself so available. True, a customer may not want your phone number on their dog’s collar, but could you do something similar — put your mobile number on all receipts or anywhere else to allow the customer to get in touch immediately?