Mobile operator O2 is launching a free wi-fi service in the UK, which it promises will be double the size of existing networks by 2013 taking it to 13,000 hotspots. O2 said access to the hotspots would be through a simple sign-up process and would be free to both O2 and non-O2 customers. The free internet access will log the customer's location and details for better delivery of targeted advertising. This will all be paid for by the venue that hosts the wi-fi router, which might also like to make use of that advertising channel. After registering your mobile number it will be confirmed with a text message. O2 then links the number to the MAC code (unique identity) of the kit connected, enabling it to automatically authorise future connections as well as spotting when the customer enters an area covered - enabling the delivery of the aforementioned advertising by text message or MMS. Simples.