How to Check Clean ESN When Buying Your Next Used iPhone

Buying a used iPhone on eBay instead of a brand-new one is a good way to save a small fortune, especially if you don’t care about owning the latest and greatest model available. After each iPhone release, online marketplaces are flooded with used models from those who can’t stand the thought of being just one generation behind.

But not all used iPhone are made equal. Sellers who know what they’re doing will mention something called ESN, or Electronic Serial Numbers. If you don’t want to waste your money or give yourself a big headache, take a moment to read our article to learn everything you need to know about these pesky numbers.

What is an ESN?

Electronic Serial Numbers are used to identify CDMA phones and authenticate subscribers to the networks. Unlike GSM phones, which use a SIM card and an IMEI number to do the same, CDMA phone usually have just an ESN. This standard is used predominantly in the United States, and it’s being gradually phased out in favor of a newer standard. This is happening because the number of available ESN identifiers is slowly running out.

What Is a Clean ESN and Blacklisted ESN?

Carriers have huge databases of phones connected to their networks. If a phone gets stolen or someone forgets to pay a bill, they can remotely blacklist the associated ESN identifier from the network. It’s impossible to activate an iPhone with a blacklisted ESN on the network of the carrier that blacklisted it. In other words, if someone got the idea that Ting’s services shouldn’t cost any money and stopped paying his phone bills, you won’t be able to activate that person’s phone on Ting’s network. Clean ESN is the exact opposite of a blacklisted ESN. It means that the ESN identifier is ready for activation.

How to Check Clean ESN on iPhone

Being unable to activate your new iPhone is a huge problem, which is why you should always check whether the ESN of the phone you want to purchase is clean. Never ever pay any money to check ESN on iPhone. There are several ways how you can do it for free.

Major carriers such as Verizon, AT&T, and T-Mobile allow you to quickly check ESN from a web browser. The same functionality is also provided by many third-party sites, like Ting or CheckESNFree.

Alternatively, you can just go to the nearest store of your carrier and ask them to check the ESN identifier for you. This is particularly useful when you’re meeting someone in person and paying for the phone with cash.

You can also head over to, a popular online marketplace for selling phones between people. Swappa has an ESN checker that you can look at, which verifies if an ESN is clean and can be activated on another carrier.

What to Do with Bad ESN iPhone

If you somehow end up with an iPhone which has a bad ESN identifier—an identifier that’s banned on your network—there’re several things you can do. The most obvious one is to ask for a refund.

All major online stores have refund policies and payment providers, such as PayPal, will almost always help you get your money back. Unfortunately, you probably won’t be able to get a refund from that shady pornstache-wearing seller from Craigslist.

If you want to use the device as you’ve originally intended, your best option is to flash it to another carrier, perhaps with AppleFlasher or a similar tool. This way, you’ll end up with a fully functional phone and a good story to tell your geeky friends.

Of course, not everyone has the time or energy or experience to mess around with carrier flashing or unlocking. In that case, you can still use the blacklisted device on Wi-Fi—perhaps as a gaming console or a very fancy e-book reader. And let’s not forget that you can always sell it for parts on a site like eBay and get at least some of your money back.

It’s worth noting that sometimes an iPhone can be listed with a bad ESN because it was marked as lost or stolen — in that case, if you go to the carrier store that the phone is with, and it is marked as such, they may ask for it to return to the original owner.


As you can see, there’s not a lot that you can do with a phone that has a bad ESN. It essentially blacklists the phone from being activated on any network out there. You can use it as a Wi-Fi only device if you want, but that’s about it.

Before you buy a device from anyone — unless you’re working with a platform like eBay who will refund you over something like this — it’s always a good practice to make sure that the ESN is clean. That way, you’re not wasting your money, and ensure that you’re not getting ripped off by the seller.