Can the network tell if you tether your PC to your phone?

Paul Ockenden explains how phone networks detect if you're using your phone's 3G connection with your PC

Paul Ockenden
6 Feb 2013

You’ll often see people explaining in various online forums that you don’t need to pay extra to tether your computer to your 3G phone, because the network can’t actually tell that you’re doing it.

Such advice used to be correct, but this is no longer true – more and more phones now send a signal to the network to ask for permission before enabling tethering, hotspot, or personal area network (PAN) modes.

If the network replies that this isn’t set up on your account, the function will be disabled on your phone. Whether or not you’re subject to this restriction depends on your network, phone and, indeed, on the version of the firmware in your phone.

For example, one of the phones in my toy box is a Blackberry 9790, and it’s on a cheapish monthly contract with T-Mobile. If I load old firmware onto this phone it will happily create a useful wireless hotspot, whereas if I upgrade to the latest OS, a check is carried out whenever I try to switch on the hotspot, and the function is disallowed.

I expect that in time all networks will support such signalling, as will most new phones. The days of stealth tethering are numbered!

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