A number of retailers already offer their customers free instore wi-fi. Tesco, Debenhams, HMV and John Lewis are among the early pioneers. Others seem certain to follow. Why are retailers doing this ? It enables them to provide mobile based services in-store to better serve customers (eg ipads for queue busting or extended product ranging) but the key reason is that its something that customers want and increasingly expect. Not to provide wi-fi risks being competitively disadvantaged and used well can grow customer engagement, sales and profits. An in-store wi-fi platform generates "big data" and a rich source of customer insight. The platform operator can see every session on every connected phone or tablet. It enables retailers to know who is in the store, when and where; how frequently they are visiting and how long they are spending there. Linking to the retailer's loyalty or CRM programme enables understanding of browsing and conversion. R...