Open the Phone app
Tap the three-dot menu or Settings
Look for My phone number or SIM status
Open Settings
Tap About phone
Tap Status or SIM status
Check the My phone number field
Open Contacts
Tap your profile or Me
Check your saved phone number
Open Messages
Start a new message
Check the sender or account details if shown
Open the SIM card settings in Settings
Check the phone number listed for your SIM
Call or text another phone and check the number that appears
Contact your mobile carrier if the number is not shown