So you’ve over the moon.

Because you have just unlocked your AT&T phone.

We hope you utilized a factory unlock solution, because this is the only legit unlock method available that whitelists your IMEI as unlocked in the phone’s manufacturer database.

Other solutions such as hardware and software unlocks are only temporary and they only keep the AT&T phone unlocked for a short period of time. This time usually comes to an end when you try to update to new firmwares and basebands; and you’re again stuck with a locked phone.

Using AT&T phone on Sprint or Verizon

After you’ve used the IMEI solution on your AT&T phone, your IMEI is whitelisted and now your phone is unlocked. This means that you can update it to new basebands and firmwares and it won’t get locked.

Also, your warranty remains intact and the resale value of your device increases dramatically than the price valued in a locked state. You don’t even need to apply any software codes of jailbreaks because the job has been done from the backend courtesy of the unlock provider.

But one of the main questions is how many carriers are compatible with your phone after the unlock? Will it work on the Sprint on Verizon network?

If you have been hoping to make it work on Verizon or Sprint, the sad answer is your device won’t work on any of these networks. Here’s why:

There’s nothing that can be done to make AT&T unlocked phones on Verizon or Sprint networks. Any AT&T that has been unlocked will be classified as ‘SIM-unlocked’ so it will only work on GSM carriers, such as T-Mobile’s GSM 2G. It won’t work on T-Mobile’s LTE, and the same principle applies to all MVNOs.

Why it won’t work on other networks is because they have CDMA radios. So you can’t make your phone work on CDMA networks as it will only function on GSM carriers, probably those outside the United States. The US itself is mostly a CDMA country; not a part of the norm though, because most of the world consist of GSM carriers. CDMA is owned by Qualcomm, which made it expensive for third-parties to manufacture GSM phones.

So your only option to switch to Verizon or Sprint from AT&T would be to buy a new phone at full retail price. The new device can be bought from a reseller, the carrier itself or a brick and mortar retail store.