I too tether without paying (Nexus 4, to my laptop). I don't usually do it too heavily and until recently hadn't had any trouble from T-Mobile.
When I moved into my new apartment I used it more than usual (maybe 2-3 GB over a few days) and they started redirecting my traffic to a "Pay for Tethering" site. It's just user-agent based though so very easy to circumvent. Other than than I have had no issues.
When I moved into my new apartment I used it more than usual (maybe 2-3 GB over a few days) and they started redirecting my traffic to a "Pay for Tethering" site. It's just user-agent based though so very easy to circumvent. Other than than I have had no issues.