You would need a new sim card but you can keep the same phone number.

Could you suggest the steps to do that ? eg. get a new SIM card, activate and port in my old number? Thanks.

You are correct.  Get a new prepaid SIM  > activate it. And you can port your number in.

To add to that, you can just activate your prepaid SIM card with any number that is available. Then when the process has finished (when your prepaid account is active). you can port in your number.

Stand by with your old SIM/phone because you will have to reply “yes” to accept the port, so don’t throw out anything until it’s all finished and done :)