Dial 123 from your BSNL number
Dial 1503 for BSNL customer care
Use the BSNL Selfcare app
Check your SIM card pack or documents
Visit the nearest BSNL customer service center
Check your phone settings under SIM information
Call another phone and see your number on caller ID
Send a missed call to another mobile and check the displayed number
Use USSD code if available in your circle
Check the number printed on your eSIM or SIM kit if provided