LG G3 Experience

[jfriend33]

Because it won't work until Verizon authorizes it....until Verizon activates it on their network. It may be compatible but until VZ ties the imei number from the phone to their network and your phone number it won't work.

What won't work? So you're saying a person can't buy a brand new Droid maxx and use it on t-mobile? Because I've seen that happen. Now using it overseas that's another story.

 

[Jeffrey]

If you have a new LTE-capable phone (Verizon calls these Global Ready phones), then you have a SIM-card slot. All LTE networks in the US use GSM technology, so newer Sprint/Verizon phones need to support both CDMA and GSM.

Depending on the specific phone, you would need the destination carrier to install software on the phone and to be provisioned with a new customer identification number (or ESNS) and the telcos are not in the habit of handing those out — not when they can sell you a new phone instead.

This said, your phone still may not work on any or every GSM network around town. It still needs to be compatible with the specific radio frequencies that your new network uses.

The catch is (and you knew there would be one) that if you do put in another GSM SIM card you may be restricted to 2G and 3G services only — 4G LTE is still locked down on many devices.

Newer Verizon devices should technically be compatible with AT&T and T-Mobile's LTE services, but it depends on the phone and whether it has built-in support for the bands of LTE that GSM carriers use. The same goes for some Sprint devices (although AT&T is still maintaining that no Sprint phones are compatible with its network).

To sum it up, while you may be able to take your old Sprint or Verizon phone to a different network, it's not guaranteed that the device will be able to access all of that network's features. It really depends on the phone model and which carriers you're taking it from and to - so you may need to check with your intended provider before making a move.