Disable Waiting for Activation Popup After my phone reboots a popup appears "Waiting for Activation This may take some time." How can I disable this? I'm using a deactivated SIM card. I would like the card to remain deactivated. This is on an iPhone 5S and iPhone6.
I faced this problem before. You can try to use this trick:


Go to Settings ~> Message and Turn Off iMessage + Facetime.
Turn on the Airplane Mode.
Turn on Wi-Fi.
Turn on iMessage like the first step. The system will ask you for your Apple ID If it is not added yet.
Turn Off the Air Plane Mode.
iMessage should work properly now.


Source.