[AT&T] Tethering Costs Extra?

[DMWagner]

I am with Alltel as of right now. I like it, but Verizon bought Alltel. In my market, Verizon has to sell Alltel to another company since the Alltel and Verizon markets overlap.

So, it seems that AT&T is looking at buying Alltel. I was looking at AT&T's website to see how they compared with Alltel in prices and plans.

I saw that they charge almost double for a data plan that includes tethering.

How do they know if a customer tethers with a Windows Mobile phone using ICS?

My current plan with Alltel there is no restrictions on how I use the phone.