It's conceivable that the '
iMessage waiting for activation' issue is just due to a minor system error that has affected iMessage, so be sure to restart your device first to rule out this option. After all, a typical reboot clears your phone's memory, reloads all of its apps, services, and key operations, and refreshes its memory.
To turn your iPhone off, press and hold the side button and one of the volume keys, then glide the power icon from left to right across the words slide to power off.
Wait a few seconds before pressing and holding the side button until the Apple logo shows in the display's centre.
