Help! Recurrent "activation required" message after upgrade to iOS 8.1

I have encountered the same problem with my iPhone 5S ios 9.3.3, I bought it second hand and it was unlocked. I tried to restore so that I could back up my phone. I tried activating with my new SIM and I got an error message "SIM CARD NOT REGISTERED". Then I inserted the appropriate SIM Card which is at&t. And now in the process of activating it, it never gets to the Home-screen. It keeps saying "Activation Required", I upgraded the firmware to ios 10.1 and still I get the error message "Activation Required" right when I click the "Get Started" which is supposed to take me to the Homescreen. Please any Solution??

I'm not sure why there hasn't been someone on apples end that has not been able to help any of us. However this is the solution that I have came to figure out. (Hope this helps everyone).

Go to:

Settings/Cellular/Cellular Data Options/Roaming/ then un-check International CDMA &/or Data Roaming.

I've un-checked both above and it was the only solution that I've figured out thus far to work.

Hi! Simply go to settings on your device (ipad or iphone) and go to icloud (it's on the same place as where you turn on airplane mode etc, scroll further down and go to "find my iphone" ( or find my ipad) and turn it to "off". It worked for me thank goodness because i'm in europe and couldn't access my ebooks, email, or use the internet.

I'm posting this here as a reply to first comment to save people from reading 4 pages of responses to get to this solution. I'll post it as a comment too! Thanks to the person who suggested this! It saved my vacation!!! :-)

Hi! Simply go to settings on your device (ipad or iphone) and go to icloud (it's on the same place as where you turn on airplane mode etc, scroll further down and go to "find my iphone" ( or find my ipad) and turn it to "off". It worked for me thank goodness because i'm in europe and couldn't access my ebooks, email, or use the internet.

I'm posting this here and in a reply to first comment to save people from reading 4 pages of responses to get to this solution. Thanks sooooo much to the person who suggested this! It saved my vacation!!! :-)

Here it is May 2017, and I'm just having this for the first time. What's different is that this is on my iPad. Whereas it does have cellular capability, I have NEVER used that, don't have a number for it, nada. Supposedly available one-month-if-needed, and I've never needed it. All WiFi. That said... same problem. How could turning off Airplane Mode have anything to do with it, if I'm always on WiFi, anyway? I've tried to run their sequence a few times, but it always fails, so I can't get to any settings, can't turn off "Find my iPad," can't do anything whatsoever. Apple continues to circle the drain. Any ideas in this scenario? Thanks.

I would talk to someone higher up when you take your phone in to your phone carrier.

Activation process - cellular data is a carrier feature.

yes i have the same problem exactly. i was locked out of my phone when abroad on many occasions due to lack of wifi.

Hi,

Exact same problem for me too.

IPhone 5, iOS 8.1.1

Tried restore to backup, restore to new phone, DFU restore, new SIM card ... nothing helps.

The phone is for most purposes useless right now ...

For what it's worth, issue went away when I returned stateside. Also had an annoying battery drain pop up that lasted until the return.

Hi mine just recently started the same problem. It keeps telling me it's linked to "Find my iPod". Have you found a solution for this yet

im having same issue with my iPad. Problem started when I had iPad removed from Verizon data plan as I wanted to only use on home wifi. Do you think this is Verizon causing the issue?