The question is simple; how can a cell provider distinguish a web request from a tethered device or the phone itself?
If the phone is acting as a NAT, how do they distinguish which packets come from which device?
My plan has unlimited data and when I signed up the provider didn't even have a tethering plan, or at least it wasn't made apparent that I would need one to tether. So for over a year I have been enjoying tethering without the ludicrous fee of $30 per month. But just yesterday they somehow decided to start detecting my tethering status. I can browse the web for ~5 minutes from the tethered device before every web-page request is redirected to a nag screen. This also forced my phone to be redirected as well. The redirection lasts for between 5 to 30 minutes. When the redirection stopped it only started again when using the tethered device.
Is my understanding of NAT incorrect? When tethering via BT PAN, USB, or WIFI I know the communication between the two devices is done with local network addresses, 192.168.0.x. If it was based on data usage wouldn't I always be redirected when I reached a certain usage? It seems a little absurd to think each packet is examined for user agent information, but other than that I don't know how they are doing it.
If the phone is acting as a NAT, how do they distinguish which packets come from which device?
My plan has unlimited data and when I signed up the provider didn't even have a tethering plan, or at least it wasn't made apparent that I would need one to tether. So for over a year I have been enjoying tethering without the ludicrous fee of $30 per month. But just yesterday they somehow decided to start detecting my tethering status. I can browse the web for ~5 minutes from the tethered device before every web-page request is redirected to a nag screen. This also forced my phone to be redirected as well. The redirection lasts for between 5 to 30 minutes. When the redirection stopped it only started again when using the tethered device.
Is my understanding of NAT incorrect? When tethering via BT PAN, USB, or WIFI I know the communication between the two devices is done with local network addresses, 192.168.0.x. If it was based on data usage wouldn't I always be redirected when I reached a certain usage? It seems a little absurd to think each packet is examined for user agent information, but other than that I don't know how they are doing it.
/www.3gtethering.com/what-is-3g-tethering/
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