Sure, my T-Mobile plan has "unlimited" data usage on my phone, but only 5G/month tethering. I can track my usage separately through their website.
Tethering is a standard feature for them now, but they used to require an add on and would track down people tethering without it. (AFAIK it was as simple as searching for desktop user agents)
Tethering is a standard feature for them now, but they used to require an add on and would track down people tethering without it. (AFAIK it was as simple as searching for desktop user agents)