How to fix: iMessage Unavailable: Turn on cellular data or use Wi-Fi to set up iMessage

Question

My iPhone 5 suddenly ceased using iMessages. The phone is unlocked, has ios 9.3.2 installed, I have very few apps installed, and no new apps installed recently.

When I go to Settings > Messages > iMessage and try to toggle, I get the following:

iMessage Unavailable
Turn on cellular data or use Wi-Fi to set up iMessage.

However, cellular data is enabled in Settings > Cellular > Cellular Data. Cellular data seems to be working fine in Safari, apps, etc. I get the same behavior with LTE or 4G cellular.

I have tried all of the following based on hunches and information gleaned from non-stackexchange sites:

• Restarting Messages
• Restarting the phone
• Resetting network settings
• Resetting the phone's passcode
• Resetting the AppleID account password associated with this phone
• Erasing all content and settings from the phone, and then restoring from backup
• Ejecting the SIM card, and replacing it.

How to get this basic functionality to work again?

Answer 1

Ok, so there's at least one solution:

1. Establish a Wi-Fi connection using Settings > Wi-Fi (switch on, etc.).

2. Log-in the iphone using AppleID when prompted.

3. Disconnect cellular using Settings > Cellular > Cellular Data (switch to OFF).

4. Switch iMessage on (Facetime, etc.) in Settings > Messages > iMessage.

5. Switch cellular data on by reversing step 3.

6. Switch Wi-Fi off if so inclined by reversing step 1.

That did it!

Also? Screw Apple! Talk about cut-rate functionality…