Possible to use iPhone on GSM and CDMA networks?

If the iPhone is activated with Verizon, you can ask Verizon to unlock the GSM side of the iPhone to use a GSM carrier's SIM card when traveling internationally outside of the U.S. This does not apply to U.S. GSM carriers such as with AT&T and T-Mobile.

Other than that, the iPhone can roam internationally with GSM carriers outside of the U.S. with Verizon GSM roaming partners in other countries.

The only phones you can use on Verizon's network are ones that were originally sold as "Verizon" phones. This is true of, as far as I know, all CDMA carriers. Verizon will unlock the GSM side of an iPhone 4S for international use for their own customers. Other CDMA carriers have other policies. The Verizon iPhone 5 and later are unlocked and will work on any GSM network.

An unlocked phone purchased from the Apple Store will not work on a CDMA carrier.

If you purchased an unlocked iPhone from T-Mobile (model A1429, does contain both GSM and CDMA chipsets, but the CDMA chipset is inactivated to Verizon), it it possible Verizon will activate the chipset in this phone? It's very unfortunate they refuse to activate a chip your phone contains merely because you bought it from another carrier. I recently assumed someone's 2-year Verizon contract and would really like to use my GSM and CDMA-compatible iPhone 5s.

stephmstanton wrote:

it it possible Verizon will activate the chipset in this phone? I

No, it is not possible.