Bad Imei.

I've had carriers mis-type the IMEI when entering the plan.

Or maybe somebody else did some shenanigans with a clone of that IMEI.

All sorts of weird is possible.

The carrier databases are not always pristine, nor necessarily consistent across towers.

Contact your carrier, and ask them about this.

It could be stolen or it could be a phone that AT&T blacklisted because of payment issues. If you have the IMEI you can call AT&T and ask.

doxaenergy wrote:

please Is it possible for a brand new unopened / unused iphone to have a bad imei on a carrier’s network?

Yes.

iPhones are designed for use on specific networks and/or in specific regions/countries. If a different cellular carrier network is used, or a different region/country, failure should be expected.

We need much more information from you. Examples:

• What country was the iPhone purchased in?
• What country is it being used in?
• What is the exact model name and number of the iPhone?
• What does “ an AT&T iPhone” mean?
• Was the SIM card replaced? If so, what are the properties of the new SIM (carrier, country)?
• How was the iPhone purchased?
• Was the iPhone locked to AT&T? If so, did AT&T unlock it?

That could only be answered by AT&T.