> whether Three have also lifted their restriction on using a phone SIM in a mobile broadband only devices.
err, if you have a SIM only contract, I'm sure you can sue them into oblivion(*) if they don't let you put it into a device of your choosing. I admit they can tell by querying the IMEI returned via the authentication and encryption routines, but you do at least still have the option of setting your phone to be the "broadband device" by turning on the mobile hotspot function (admitedly probably with limited range in comparison with a proper router). But equally, from your link:
> Since we opened our investigation in March 2018, Three has confirmed that it has already:
> ...
> withdrawn restrictions on the use of handset SIMs in dongles and mifis
(*) YMMV, IANAL