1. Send an sms from your current sim to 1900 with text PORT <10 digit mobile number>, and immediately after sending the sms you will receive a 8 digit code.
2. Go to the customer care desk of the telecom company to which you want to port your number and ask for the forms to be duly filled by you with mentioning the code received by you earlier.
3. Apply for porting the number by submitting your id and address proof.