Hello VRec1,
If this is happening while making a cellular call using the Phone App, contacting your phone carrier would be your best option. An iPhone should automatically show your phone number, if you have your caller ID enabled, based on information from the SIM card. You can see and possibly update your number in the Settings App > Phone.
https://support.apple.com/guide/iphone/make-a-call-iph3c993cbc/15.0/ios/15.0
You may be using FaceTime Audio to make the calls which does allow you to set a default caller ID. This setting is located in the Settings App > FaceTime . The caller ID section would allow you to check your phone number rather than email address.
Below is the relevant section from the iPhone User Guide section I linked above about the Phone App caller ID.
“Change your outgoing call settings
- Go to Settings
> Phone. - Do any of the following:
- Turn on Show My Caller ID: (GSM) Your phone number is shown in My Number. For FaceTime calls, your phone number is displayed even if caller ID is turned off.
- Turn on Dial Assist for international calls: (GSM) When Dial Assist is turned on, iPhone automatically adds the correct international or local prefix when you call your contacts and favorites.
- For information about making international calls (including rates and other charges that may apply), contact your carrier.”
I hope this helps.
