people have had good luck on ATT swapping sims between data only devices
meaning between hotspots and tablets
the results of putting a sim from a cellphone into a hotspot, have been less often and in some cases unsucessful
AFAIK .. in all cases of success between phone and hotspot
it was an unlocked hotspot
i would be leery of buying a hotspot router and trying the phone SIM in it
if it doesn't work, you have a new paper weight
try reading ATT topics on howardforums.com and see if that has been done
i moved my Mobley hotspot SIM into a different AT&T hotspot, but many people have done that
