New Apple iPads purchased for use on the Verizon Wireless 4G LTE network can also run on AT&T's data network when an AT&T SIM card is inserted in the Verizon device, early buyers have found.
Representatives of AT&T and Verizon separately said they had no comment on the discovery when contacted by Computerworld.
In both cases, a micro-SIM card from an iPhone 4S running on AT&T's network was inserted into a new iPad from Verizon Wireless, taking the place of the existing SIM card. The iPad's carrier setting also had to be updated to support connections to AT&T in both cases.
Also, in both cases, the AT&T SIM card worked over AT&T's 3G network, but not its faster LTE network. The Verizon iPad supports the same GSM frequency bands for non-LTE bands (including EDGE and HSPA+) as for iPads sold for AT&T, hence the interoperability.
Part of the beauty of GSM networks is that they rely on using SIM cards that carry a user's account, phone number and identity from device to device, so it may not be all that surprising that new iPads can run on both networks. MacRumors theorized that Apple could have restricted the AT&T SIM card's operation over other networks but chose not to.
Because Verizon's 3G network is not GSM-based, it doesn't rely on the use of SIM cards, so there would be no Verizon SIM card (from another device like an iPhone) to insert into an AT&T iPad.
That fact would seem to give Verizon an advantage over AT&T when it comes to selling the new iPad, since people who buy Verizon iPads could use both carriers' 3G data networks, while people who buy AT&T iPads wouldn't be able to do that.
On the other hand, Verizon users would still need to buy a SIM card from AT&T, and since the AT&T SIM card reduces the capability of the Verizon iPad from 4G to 3G, industry officials questioned whether the newly discovered capability is all that valuable. A SIM card from AT&T won't work inside a Wi-Fi-only version of the new iPad.
Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed. His email address is firstname.lastname@example.org.