[Q] Can I use my phone sim (TMO) in a Gear S?

[Pedro2NR]

I'm going to start running and I don't want to carry my phone around. I am looking into buying a used Samsung Gear S for my runs (answer calls if/when needed & play music).
I searched but I couldn't get a straight answer.
Can I use my current sim card (nano) to the Gear S when needed? Will TMO locked my sim out if noticed?
I don't plan to use the watch other than when I don't want to carry my phone (running or other sport activity).
Thanks in advance

 

[Pedro2NR]

Anyone know the answer? I also heard that it is best to buy an unlocked (AT&T) Samsung Gear S.

Any information is appreciated.