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No, AT&T and Verizon use different radio frequencies. A SIM from one wouldn't work on the other, at least not at LTE speeds. I think it might be possible to stick an AT&T SIM into a Verizon iPad and get 3G speed, but I'm not sure. The other way would definitely not work, because Verizon doesn't use SIM cards for their 3G network.
 
No.

Can I just switch out the sim card (or whatever it is called) to go from an ATT iPad to make it a Verizon iPad?

One network is GSM and the other is CDMA the never mix Unless your ipad is world mode, and none are made world mode.
 
the iPad 3's are "world" mode iPads. u can place a VZW LTE Sim into the AT&T version and it will work but it won't receive LTE speeds. it won't work AT&T to VZW though. both will work over seas and receive 3G speeds for now
 
the iPad 3's are "world" mode iPads. u can place a VZW LTE Sim into the AT&T version and it will work but it won't receive LTE speeds. it won't work AT&T to VZW though. both will work over seas and receive 3G speeds for now

AT&T service will work in Verizon iPad
Verizon service will not work in AT&T iPad
 
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