Yes. you may continue to use your mobile number once the upgrade from 4G to 5G plan is completed.
During the process of upgrading from 4G to 5G plan, you will be given a temporary number on your 5G physical SIM/eSIM.
You may continue using your existing physical SIM/eSIM until the temporary number on your 5G physical SIM/eSIM is replaced with your original mobile number.
Number porting will take 1-3 working days. An additional 2 - 7 working days is required for the delivery of physical SIM (number porting will only commence after you have activated your SIM card).