Do you suspect if your imei is blocked?  Here are ways you can tell.

Craigslist is full of people who would sell you an IMEI blocked phone. 1.  Put a working sim card in the phone you want to check.  For example, you can use your friend’s T-mobile sim card to see if T-Mobile has imei banned the phone that you are trying to use on MVNO networks that are under T-Mobile.  Simple Mobile, Ultra Mobile, Family Mobile, Go Smart will all most likely not work at all if T-Mobile IMEI bans a phone since they all use T-Mobile’s towers.  T-Mobile will program banned IMEI’s into the towers itself so there is no way around that ban.

You can visit http://www.t-mobile.com/verifyIMEI.aspx to check the IMEI, T-Mobile and other carriers use same database now so if T-Mobile says it is blocked, it should also be blocked with other Carriers.

2.  You can also find out by calling T-Mobile, AT&T, Verizon or Sprint and ask them if an IMEI is banned.  AT&T has adopted a new policy and it varies with rep you speak with, but they will tell you that you have to go into a store to check if it’s banned or not. AT&T wireless number 1-800-331-0500 You can unlock the phone that is imei banned and use it on a different carrier which works well, although soon all carriers will start combining databases of Renegade devices so keep that in mind.

Unsuspecting people are being ripped off on craigslist with phones that are IMEI banned.  Make sure you have a working sim ready if you are going to buy a phone from Craigslist, so that you can test out the phone before buying it.  Often times, a phone a person is selling may work fine and a few months later get banned. Whatever you do, don’t go to those people that spoof by flashing IMEI’s of other phones to bypass the Tower IMEI block.  This is illegal and carriers serious consequences. You will also loose 4G if you get your IMEI flashed to a different IMEI number.  I haven’t heard of someone convicted of doing this yet, but in UK it is like a 5 year sentence.  In USA it’s a 5 year sentence.

Good luck repairing an iPhone 6s or 7 IMEI, an entire system board replacement is needed to change the IMEI number on the new iPhones.