I can't activate my iPhone 6s Plus

Start here: If you can't activate your iPhone - Apple Support

See here.

After reset, my iPhone cannot be activated

I try my best for that. I'm waited solution for 3 days, there is no official respond yet. And I can not accept upgrade iOS. I am pretty sure my hardware and current iOS have no problem.

It's doesn't work. I don't want to upgrade my f**king iOS. Apple didn't tell me that needed upgrade iOS if reset my phone before. I am shamed for apple.

Forcing users to upgrade iOS version and didn't tell before, it's illegal behavior. In future, Apple should be facing class action.

Ranting about it isn't going to do you any good. If you actually want help, you need to calm down and tell us what your problem is.