The ones in Australia where one way - you could search for a name and it would give you a phone and address... but if you a programmer, you could read the datab

The ones in Australia where one way - you could search for a name and it would give you a phone and address... but if you a programmer, you could read the database directly, so search on a phone number and get back the address and name, or search an address and get back name and phone number. There were a few services in the early 2000s doing this, they were called Reverse Grey Pages