Several users have reported that iMessage app keeps showing their old phone number after they changed their phone number. If you encounter this problem on your iPhone, try these steps to attempt to resolve the issue:
To fix this problem, try turning off iMessage (Settings > Messages), then restart your phone (by pressing and holding the on/off button), tap Settings > Phone > My Number and confirm that it is correct. If it is not correct, please enter the correct number), then turn iMessage back to On (Settings > Messages) and go to Settings > Messages > Send & Receive and see if the correct number is displayed under “Start new conversations from:”.
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