For Prepaid Users:-
1) You should have non-docomo Network Enabled Mobile with you.
2) Now SMS PORT to 1900. For Ex. Your number is 9876543210 then write PORT 9876543210 and send it to 1900.
3) You will receive message from 1900 stating your UPC Code.
4) Now, go to nearest TATA Docomo retailer and purchase new SIM and they will give you one application form also.
5) Mention UPC code in application form and fill all other details and submit it there with Passport Size photo and Valid Address & ID Proof. (Don’t replace your new Tata Docomo Sim with old SIM.)
6) Once Tata Docomo will process your form, they will send you one message to your old number stating that your application have been verified and also message will have exact date when your number will be ported to Tata Docomo.
7) Now, replace your Old Sim Card with New Sim Card of Tata Docomo on given date in message.