Update the mobile number on your profile in IRCTC. They will sent a verification code to your new number and next time when you log in, it will ask for the verification code, enter the code and you will be successfully logged into the IRCTC. Go to booked history choose you pnr and clink SEND SMS............and you will receive SMS. Note: Now i think there is restriction for Number of sms per PNR, may be 3 SMS or just 3 days before the journey (don't know the latest update exactly)