Best answer by daniiiiiv
Welcome to the iD Community.
Anything that connects to your phones hotspot is considered tethering.
Below, i have attached a reference from a similar case found from: https://community.idmobile.co.uk/bills-allowances-charges-capping-21/is-there-a-charge-for-tethering-621
Whilst the Terms & Conditions advise not to Tether, it's not explicitly a case of
"do it and you will face repercussions"
There isn't a punishment for tethering to answer the first question. We simply don't provide support for it, so where some customer's have advised they could not get it working, as it's not a feature we support, we can't help in getting it set up. I hope that better clarifies this for you.
Leading onto the second, If you tether and stay within your mobile data allowance, you will not be charged extra. The charge is applied when you go over your inclusive data.
Please follow the link i provided above for a more comprehensive response.