One of the main source to get personal details would be from Yellow Pages. Anyone can check your full name, home address and home telephone numbers just by searching Yellow Pages residential listings or from their phone app "CALLMYNAME". Apart from that, our personal contact information are put up online without our approval, and yet we have to take the trouble to opt-out from such dangerous service. This could possibly lead to serious damages done by scammers from overseas to scam any innocent family through a fake contest winner notification (in the form of sms or call).
Another source would be from local telecommunication providers. If one do not pay a fee to privatise their numbers, their number would be published everywhere, taking away their privacy. Unknowingly, one’s number could be sold to another company and 10-20 subsidiary/related companies. These fees are charged can literally be called extortion, which are totally ridiculers.
Currently, I see the irony on how the government is trying to tackle its citizens’ contact privacy issue. On one hand, they are claiming to assist their citizen from unwanted calls and messages; on another hand, they are allowing companies (such as Yellow Pages) and telecommunication providers to reveal people private numbers. I cannot see any effectiveness in what the government is doing.
There are definitely improvements to make. Yellow Pages should stop publishing residential listings or any personal contact details through any app and just provide the only service for businesses to advertise their brand name/contact details. Telecommunication providers should automatically keep every private and confidential without any charges. I believe only then people numbers can be protected.