Chosen Solution
I bought an iPhone 6 plus (Verizon) to work on my ATT and it has no service. I tried all the fixes that are online and nothing works, I also tried with another Verizon sim card and nothing. When I go to about, on network there is none but on carrier shows ATT. any help?
If it’s stuck on no service its very possible the imei/esn is blacklisted. If it goes back and forth between searching and no service its a different issue. I agree, go to swappa.com and checkesnfree.com to rule out blacklist. Then I would continue to rule out a software bug then move onto hardware. Go to settings , general and reset network settings. Try restoring through iTunes and not just on the phone itself. Then I would open the phone and proceed to hardware such as making sure your signal antenna (attached to your dock connector/charging port) is properly connected.
