Q: iMessage not working since security update

GiantDan wrote:

 

IMessage not working after latest security update. Phone is ATT IPhone  6Plus

Use Messages with your iPhone, iPad, or iPod touch - Apple Support

If you can't send or receive messages on your iPhone, iPad, or iPod touch - Apple Support

If you get an error when trying to activate iMessage or FaceTime - Apple Support

no idea what not working means, so I provided you 3 links to look at.

GiantDan wrote:

 

Sorry. Cannot receive IMessage on my iPhone .Stopped working after latest security update.

IMessage will not activate

Then take a look at the last 2 links I provided to resolve the issue.