Do you have a mobile service elsewhere? If so the easiest way is to send the word STAC to number 75075, you will gets STAC code by reply or further instructions such as adding in your date of birth to the word STAC.
You then go to the number porting page of your current network and give them the STAC code a few days later your virgin number is cancelled but no number moves.
STAC is like PAC except the number does not port.
if you don’t have another service anyone can use your STAC code.