Free Wi-Fi? Surely there's a catch? Well no, there is no catch. As long as you are in the right part of London, Wi-Fi is yours, saving you a good chunk of your monthly data allowance if you box clever.Nokia is the name behind it, but the company providing the infrastructure is Spectrum Interactive, an independent Wi-Fi operator in the UK that offers services from hotels to airports and in this case, via old school phone boxes too. Specifically phone boxes in areas including Oxford St, Tottenham Court Road, Bloomsbury, South Kensington, Knightsbridge, Mayfair, Lancaster Gate, Westminster, Sloane Square and Victoria.To access the service. fire up your smartphone and look for Free Nokia as a Wi-Fi service. Accept the terms and conditions and you'll be online for free, as long as you stay in an area that picks up the signal. After the initial login, you will be recognised and connected automatically when in range. If you've got a Nokia phone, you do get a bonus though - the hotspots are marked on Nokia Maps.Right now, it's only a limited trial running from now until December, after which Nokia will no doubt assess its effectiveness. It must have one eye on the longer term though, as the company is already talking about expanding the service to other cities. In the meantime, give it a go and let us know what you think.