the iPad already has tethering, and the iPad itself could provide up to 10 hours of mobile hotspot on batteries.. how much hotspot do you get from that cradle point?
putting that aside, as long as the cradle point wasn't locked to another carrier , i think the sim would work fine.
a sim card that did not have tethering provisioned, probably wouldn't work.
get a good return policy on the router
-------------------------
I wish people would ask me TRS-80 questions