Apps clone your SIM card for use data different devices one at a time?

[InGearX]

in short I have AT&T

if I do this https://www.quora.com/How-do-you-clone-a-SIM-card

1. how illegal is it? will FCC care? will AT&T / T-Mobile care? who else?

2. in step 7 - can I only get the " SIM unlock code" only from my provider?

3. if I accidentally turn on two or 3 devices with same cloned card - will this raise flags with AT&T / T-Mobile ? will they block the SIM? will it be trouble ?

4. I think there were a few other questions I wanted to ask

so please help me out - what else I need to be aware of?

WHY?

this will simply save me time and effort of constantly taking out my nano SIM card from my Galaxy Tab S2 8" (my primary device) and putting it into an adapter for a regular SIM card and putting it into my Galaxy Note 3 - I use it when I go running or when I go clubbing / out ... and occasionally putting it into my other devices ...

So I am paying for one SIM (AT&T prepaid talk+text+6GB) card but I use it in Tab S2 and Note 3 and LG G2 ...
So no harm done ...

just convenience - providers should offer this service ... much like paying say for Netflix or Hulu or Amazon Prime ... do you pay for every device you want to use the service on? No

But carriers know they could offer this - but they want you to - because they want you to pay for every device ...

OK please advise ...
thank you ...