If you get hold of a used Verizon iPhone, you may be interested if it can be “unlocked” to work on another CDMA network like Sprint. The short answer is that it’s possible, but a hack will be much harder and have different legal ramifications from traditional GSM-iPhone unlocking, (which is now legal). The reason is, due to the sim-cardless nature of CDMA networks, it’s up to the carrier to give an individual phone permission to connect to its network. With CDMA networks, you are identified by your device. With GSM, you are identified by your sim card.
For an iPhone to connect to Sprint’s network, Sprint would have to give that specific iPhone permission. Historically, Sprint has not allowed “foreign” smartphones to connect. Their probable motivation is they want you locked you in to a two-year contract by forcing you to purchase a new (subsidized) iPhone.
Mobile Equipment Identifier (MEID)
When it comes to locking down CDMA phones, networks previously used something called an ESN (Electronic Serial Number) to identify specific phones. Because those numbers ran out, they now use a Mobile Equipment Identifier (MEID), which the Verizon iPhone uses. CDMA networks check a device’s ESN/MEID before allowing it to connect.
In the past, Sprint has not given permission for “foreign” ESN numbers to connect their network. Better possibilities are that the smaller regional CDMA networks like MetroPCS, Boost, or Cricket will look the other way and let the Verizon iPhone connect to their networks, but there could be legal ramifications from Apple/Verizon for doing this, especially if an exclusivity agreement is in place (Apple’s Tim Cook says there isn’t).
Can the MEID (or ESN) be Hacked or Changed?
In the past, people have hacked (switched) the ESN on cell phones, but it’s also likely illegal, possibly fraud. Because people have figured out how to switch an ESN, it’s no great leap in logic to think a MEID-switch hack is possible, or that an MEID can be changed to ESN, etc. But the legality question makes it unlikely that the common citizen would want to risk it.