Was unaware that is all thats needed to transfer a number. Thought about porting a number to Twilio, then to have 2 phones which one would have to pay for and

Was unaware that is all thats needed to transfer a number. Thought about porting a number to Twilio, then to have 2 phones which one would have to pay for and just switch the call forwarding. I'll check out the sim card solution, thanks for the info!