Dial `*123#` from your BSNL SIM and check the USSD response
Dial `*222#` and look for your mobile number in the message
Call another phone from your BSNL SIM and check the caller ID on the other device
Open the BSNL mobile app or self-care app and view your registered number
Check the SIM card pack or original SIM documents for the printed mobile number
Contact BSNL customer care and verify your number after authentication
Send an SMS or make a call to a trusted number and ask them to read back your number