Iphone 5 BAD IMEI what's that?

I want to buy an iPhone 5 for tmobile on eBay, I found one I could found but it says Bad IMEI what is that?

The phone has been blocked by the carrier's network because of one or more possible factors. The phone may had been stolen, lost or not paid for, and in event of that the carrier is required to ban it from the network and in a best case scenario, it can only be utilized as an iPod.

Best of luck!

I would not buy any phone with a 'bad IMEI"

http://techpayout.com/imei-number/

IMEI stands for International Mobile Equipment Identity. Similar to an ESN, a phone has a different IMEI, just like every human has a different fingerprint. Phone carriers use your IMEI to monitor whether your account has any past due bills or has been reported as lost or stolen. The IMEI number is used for GSM phones and is similar to how MEID numbers are used for CDMA.

Before buying or selling a used phone you should always make sure the IMEI number is "clean"

What is a Bad IMEI?

Your carrier may tell you your phone has a "bad" IMEI. This means that it can't
be activated with them. If the phone is yours, you either likely have an overdue
balance on your account or had previously reported it lost/stolen. In speaking with
your carrier you should be able to resolve this. If you received a phone with a bad IMEI,
you will need to contact the previous owner and have them try to resolve it.