thanks, all. the clear consensus is to play it safe and keep another number.
fyi, for all bros out there, if you live in town, get a second number by buying a prepaid siim card at the local 7-11. cost is less than HK$100, and it will last for months if hunting is all you use it for.
last thing anyone needs is to have a mamasan/papasan/girl calling you or sending you an sms at the most inconvenient time.