Either you get rid of unlimited accounts and charge by the GB, in which case it shouldn't matter to you whether those GBs are from the phone or tethered. Or you restrict tethering because people on unlimited accounts are using too much bandwidth while tethered. Charging for tethering while at the same time charging per GB is trying to have your cake and eat it too. The FTC should step in and make it illegal to advertise bandwidth as "x GB" if the carrier puts restrictions on exactly what is and isn't allowed in those GB. At the very least it should come with an asterisk and a disclosure of limitations at the bottom of the ad. That way people know not to compare GB* to GB.
Good luck trying to impose that. I might be shooting my karma, but what the phone companies are doing is not illegal, and it isn't unexpected. Just like a private person has the right to decide whether you agree to the terms set by contract, the company has right to decide whether to sell you the contract or not. If you do not agree and think this style of contract is making them lose huge amounts of business... Go ahead and start your own telecom company.
Assuming they are doing it by packet inspection: Just run a strongly encrypted VPN to your home server, and use that internet connection. All Verizon will see is VPN traffic, which is legal.
At the point that you connect to VPN using cell phone, it's semi-obvious you're tethering.
Then again, I don't own any mp3 players or phones with cameras.
Sorry, Sir! I will get off your lawn momentarily!
Immigrants and illegal immigrants are not the same thing. America was not built on illegal immigrant labor.
Tell that to the indians.
Your countries are often at fault themselves. For example, many European nations insist on translating US programs into the local language.
That's mostly just France you're thinking of.
It is not every question that deserves an answer. -- Publilius Syrus