McDonalds conducts Mcdvoice survey in the official web-site where customer insights from the Survey questions will be received by the McDonalds USA restaurants to understand & satisfy customer needs and behaviour. These customer findings obtained by logging into its survey site : www.mcdvoice.com . The 7 days from the date of purchase is given to Customers who participates in the surveys are eligible to win free sandwich on their next visit (Complete the survey from here).