Apple iPhone owners who've upgraded to iPhone OS 3.0 have been told by O2 not to tether their phones to laptops in order to enjoy free 3G connectivity of their PCs. O2 says it will disconnect anyone who attempts to use their iPhone as a modem without paying the necessary charges.

Along with the launch of the iPhone 3G S, O2 today launched its iPhone OS tethering Bolt On. But there are several hacks on the internet that allow you to use the iPhone's tethering capabilities without using the Bolt On.

O2 has quickly fired a shot across web-users' bows, telling Techradar: "Internet rumours suggest that some customers have modified their iPhone to enable Internet Tethering without the purchase of the Internet Tethering Bolt On.

"Any use of this particular feature without the purchase of the Bolt on is specifically prohibited under our terms of service.

"Under those terms we reserve the right to charge customers making modem use of their iPhone or disconnect them.

"If customers wish to use the Internet Tethering feature on their iPhone 3G or iPhone 3G S, we recommend taking the Bolt On which is available from Friday 19 June."

O2 hasn't given any details of how they would detect illegal tetherers, or enforce the ban.

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