McDonalds organises a customer satisfaction survey in the name “MCDVoice” at the official site www.mcdvoice.com. Customers who dine-in at McDonald’s restaurant will receive a printed receipt soon after the purchases. This survey code on printed receipt is mandatory in-order to take mcdvoice.com survey . After you complete your dining at food stores, make sure that you secure the McDonald's receipt at the safer place (Begin the process before the print on receipt wipes off). As mentioned, Customers need to Take this Mcdvoice Customer Satisfaction Survey at the official site of MCDVoice within 7 days of your last purchase to win the Free Sandwich upon purchase on any Sandwich.