u/ezksymtal, there are some steps you may need to do for iMessage to get it to re-activate and work.

- do you have 2fa (two factor authentication) enabled for your apple id?

If no, then

- make sure you sure you click on your itunes account and verify you can see your account

Settings click on your account at seen at the very top

- click on password and security

provide your password and make sure you can see the details, then close that and get back to your account

- click on payment and shipping

make sure you have at least one registered payment method (that is NOT listed in red, that means you have to re-authenticate that payment method… in such case, do what is needed and when done, then close out of that to get back to your account)

- click on media purchases - view my account

you should be able to see your account

or

If yes (that you have 2fa), then continue immediately below

In iMessage click to login to with your apple id to use with iMessage (which you can deactivate later) and verify that you have a check mark next to your email account to send / receive iMessages (and the same should be for facetime)

you may or may NOT have the check mark on your cellular phone number, then

go back to the iMessage main scrren and on the iMessage main screen where the toggle for imessage is located and should be toggled on, then toggle it off

iMessage should be toggled off / turned off (but you did NOT log-out of your apple id for imessage)

then

toggle iMessage back on

click on ‘send receive’ (which is immediately below the imessage toggle) so that you can get in the list of accounts that are available for imessage

you should see a check-mark next to your email account (as it was before and since you didnt’ log off your apple id for imessage, then)

if you do NOT see the check mark next to your cellular phone, then manually click it - it will go through.

Keep in mind, that in some countries (for example UK, Ireland etc), there are requirements that need to be met… for example:

- that your cellular account is set up by the carrier for imessage

- that your celluar account is enabled to received ‘short’ number SMS messages (and send as well)

- in some countries (UK / Ireland to name a few), you may need to have your carrier ‘white list’ the IMEI of your device.

Since you don’t know if these requirements apply to you, I suggest, you first try in the order as described, one step at the time and see if your iMessage activates.

Make sure you update this post AFTER you’ve completed the above steps and go from there.