I'm having a similar issue to the one noted on this forum: https://community.sprint.com/t5/Problem-Solvers-Archive/Unlocked-iPhone-6s-not-activating-with-sprin...
No one seems to be able to help me, but my phone connects to Sprint towers briefly, and then proceeds to give no signal. I've spent countless hours with tech support from Sprint and Apple. For some reason the phone will not connect even though it's been activated on Sprint.
I'm ready to give on Sprint. Thought that they had a pretty good deal, but I'm going to go elsewhere unless I can get a solution here.
The version A1866 is not supported by Sprint. We only support the following models:
It would seem that we don't support the model you have. That would be why you are having the issues.
That is completely my mistake. I am sorry for that. Go ahead and send me a PM with your account details. I can take a look to see what we can do.