Owners of the Apple iPhone 3G and the new iPhone 3GS handsets can easily get around charges that providers apply if users want to use the handset as a mobile broadband dongle.
Currently O2 charges £14.68 per month for the tethering option which allows the user to turn their handset into a wireless modem with a monthly data download limit of 3 Gb.
However, the iPhone enthusiast site benm.at, is offering a small piece of software that activates the tethering option completely free of charge.
This could mean problems for O2 which is the only provider of the iPhone in the UK and is looking forward to huge sales of the newly released iPhone 3GS.
O2 says that tethering without paying for it is prohibited under its terms of service.