Too often you hear about people buying a used phone only to find they are unable to use it.

What a waste of time and money!

If you decide to buy a used phone follow these tips to keep yourself from being scammed.

Above all be cautious.


When buying online, find a well-known and reputable website. There is a huge market for buying and selling cellphones online and there are many websites offering this service. Do your research. Make sure the site regulates what is sold. Look for companies with a return policy. Use websites that hold their sellers responsible for their products and how they are presented. Stick to the big names if you are unsure, like Amazon and eBay.


When using Craigslist, meet in a public place. One of the best places to meet is at a cell phone store. The store can check to make sure the device can be activated and help you do so.


One of the most important parts of buying a used phone is to insure you will be able to use the phone.


So, what do you need to look for?

First, make sure it is compatible with your service provider. For example you cannot use a Sprint phone with AT&T service. Most cellphones are locked to a phone carrier/service provider. Some phones can be unlocked to be used on different networks. Phones that use the GSM network or SIM cards, such as AT&T and T-Mobile, can be unlocked to work with any SIM card. [For questions about unlocking phones and help doing so come to Tech Armor, Hawaii’s Top Rated Cellphone Unlock and Repair Center.]


Next you need to make sure the phone has a clean ESN or IMEI. I am sure you have seen the term “bad ESN” while shopping for used phones. What exactly does this mean? Bad, Clean, Blacklisted? Cellphone providers and law enforcement agencies have created a “Blacklist” to identify stolen device and keep them from being activated. The hope is that if a stolen phone cannot be used, then phones will be less likely to be stolen. When a phone has been reported lost or stolen the IMEI(International Mobile Equipment Identity) or ESN (Electronic Serial Number) is flagged. These numbers are your mobile device’s unique identifier. If that number is flagged in the system the phone cannot be activated. There are several reasons a IMEI or ESN may be flagged: it has been reported missing or stolen, the service provider has blocked it due to outstanding balance on a phone bill, or the device is financed and the original owner is still responsible for payments.


How do you know if a phone’s ESN is clean?

First step, find the ESN. You can do this in a few different ways. Most phones are marked with it either on the phone itself or with a sticker. For iPhone 4/4s you can find the IMEI on the SIM tray and iPhone 5/5c/5s on the back of the phone. (You may want to double check these with another method as both parts can potentially be non-original.) For non-iPhones check for a sticker under the battery. If the battery is not removable, check for a sticker on the back of the device.


You can also find this information in the phone’s software. One quick, easy method to try – open the dialer and type *#06#, this will display the IMEI number. Or you can check the phone’s settings. On iPhone go to Settings > General > About and scroll down to IMEI. On Android devices go to Settings > About Phone > Status and scroll down to IMEI.


So you have the phone’s IMEI, now what?

Now you need to make sure it is clean and ready to activate. To do this you can check with the carrier by phone, website, or in person. Also, many websites that buy and sell phones have ESN checkers. Or you can head over to Here you can check the IMEI against the US IMEI Blacklist database. If the results come back as blacklisted, blocked, or financed, don’t buy the phone, it cannot be activated.


Here are a few other things you might want to check.

If you are buying an iPhone check to make sure the phone does not have an Apple ID active on it and that Find My iPhone and iCloud are turned off. Apple’s latest iOS uses the Apple ID, iCloud, and Find My iPhone to prevent access and activation by anyone other than the owner (for more details check out the Find My iPhone blog entry). Trying to restore or activate the iPhone will cause it to become “activation locked“, rendering it useless without the original Apple ID and password. If the phone belongs to the person selling it they should be able to remove this for you. If they cannot, don’t buy. It cannot be activated and you will find yourself the proud owner of a fancy, new iPhone shaped paperweight.


You should also check to make sure the phone is not passcode locked. A safe thing to do is have the seller reset the phone with you. This will prevent any unforeseen problems like software locks, passcodes, or spyware.


Above all, if anything seems shady or off about a potential buying situation, don’t buy! Your gut instinct is probably right and it is not worth the time or hassle. Possession of a blacklisted phone can get you in legal trouble even if you purchased it unknowingly.

Happy hunting and stop in to your neighborhood Tech Armor to unlock your new phone or activate prepaid service.