For 3 months yes. After that, you have to enter into some kind of rolling contract, be that one of the GB plans or £3.50 a month flat fee paying 2.5p/MB PAYG on top of that.
If you don't wish to do that, they terminate the SIM, which is then where they get you with their charges, as it will cost £20 to have it re-connected.
The general impression I get from reading their t&cs is they wish you to contract in some kind of fashion, even if it is only for one monthly rolling (they give you a better deal if you do 3 months). But for the likes of me who really only uses mobile data in my hotspot device a couple of days a month (if that), I think I will stick to my O2 SIM for the moment and just get billed a pound per day (maximum) when I activate/connect the device to their network. Plus I have the option of 4G on that (if I purchase a 4G tariff) - I don't believe mobi-data is 4G at all yet.
Edited by deleted (Wed 30-Apr-14 22:01:39)