I Message
My I messages are set up to another phone and I can’t seem to chance it as it’s greys out with awaiting activation next to it.
im unable to send I messages or use FaceTime
Question marked as
Messages - If you get an error when trying to activate iMessage or FaceTime. https://support.apple.com/en-us/HT201422
Messages Troubleshooting. https://support.apple.com/en-us/HT204065
Do you have access to another WiFi network where you can try? That has worked for several people.
Try a restart.
Restart your iPhone, iPad, or iPod touch https://support.apple.com/en-us/HT201559
Try a forced restart.
Reset Device. https://support.apple.com/en-us/HT201412
If necessary
Hard reset. https://www.wikihow.com/Hard-Reset-an-iPhone
Do a backup and try a factory reset. Then restore from your backup.
Restore to Factory setting. https://support.apple.com/en-us/HT201252
Backup - Restore your device from an iCloud or iTunes backup. https://support.apple.com/en-us/HT204184