As third-generation iPad units have started to land in the hands of customers in the US, a few new details about the 4G models’ behavior have been discovered. As noted by Mac Rumors forum member jsnuff1, it is possible, thanks to the GSM roaming capabilities of the Verizon 4G model, to install an AT&T micro-SIM and access that carrier’s EDGE, 3G, and HSPA+ 4G networks. Doing so requires applying the AT&T APN carrier settings first, but is encouraging for those wishing to take advantage of the faster non-LTE networks offered by AT&T. In addition, iLounge’s own Jerrod H. has discovered that iPad users who are upgrading from prior 3G-enabled models and currently have grandfathered-in unlimited data plans need not swap SIM cards with their prior units, but instead simply need to sign in with the same account information, and the unlimited plan will appear as an option. In any case, swapping SIMs is not recommended, as older SIMs are unlikely to support LTE service.