[hugh3]

You pay for the data you transfer. Tethering is simply an "unauthorized" (by the vendor) use of that data

Wait, does anyone charge a per-kilobyte data charge? I thought most plans either had unlimited data or some large cap.

[chris_j]

In the UK, most providers charge per-kilobyte. For example, I'm on a contract that gives me 1GB per month. Anything beyond that and I pay extra. It annoys me greatly that tethering isn't included in that (and costs a lot more), whether or not I use the 1GB that I've already paid for.