@devu, no. Nothing to do with it.

O2's fair usage is unofficially 500MB per month too. The first you hear is a text message and a temporary disruption to your data service.

Then you get a letter or two saying that you are breaching the rules on either streaming or tethering.

Then they may, though I am not aware of anyone getting this yet, charge you for the extra data.

Mind you, when I got the letter, I called them to see what they thought they knew. They said that they weren't that bothered but to keep an eye because they might throttle my connection after the 500MB is hit.

Fair usage should mean that. Simple as. If they don't have a network that can support it, don't advertise it. Ofcom (UK) have looked into this. Google it.