Susanlixx:
He needs a burner phone for the same reason I do and all of us do. it is legal but do you really want the Hong Kong government knowing what you are doing?
The police can arrest girls for breaching their visa (coming here is tourist and then working), they get their phone and see all the messages from all the punters, including you and me. They could easily harass us, extort us, blackmail us, or do anything they want.
Legal does not mean "OK". Legal means you can do it. Think of all the people who you would not want to know you are undertaking this legal activity.
HK_Legend has a way to make it work. I, alas, do not. I have a second mobile number and Have last month (prior to the deadline the end of this month) given the the SIM car provider a copy of my HKID.
Keep on mongering
