I guess the question of whether Verizon knows about this is answered here.
AT&T is telling users of free tethering that they have three options:
1. Stop using free tethering.
2. Contact AT&T to activate a legitimate tethering plan and start paying up.
3. Go ahead and keep tethering, and AT&T will automatically sign you up for a tethering plan and bill you.
Also known as mobile hot-spotting, the official tethering service provided by both AT&T and Verizon costs an additional $20 per month on top of data and voice plans. Free, unauthorized tethering has been accessible on the iPhone for years, and AT&T is only now beginning to crack down on people using the service without paying.
Weve just begun sending letters, e-mails, and text messages to a small number of smartphone customers who use their devices for tethering but arent on our required tethering plan, an AT&T spokesman told Wired.com. Our goal here is fairness for all of our customers.
AT&T told Wired.com that its able to determine if a smartphone customer is using the device as a broadband connection for other devices, which isnt surprising, because telecom carriers carefully monitor our mobile activities, counting the number of texts we send, voice-call minutes placed, and data used per month.
Its unclear whether Verizon will take similar action on smartphone customers using free tethering tools. Verizon did not immediately respond to a request for comment.