1980s
In the mid 1980s, 6-digit numbers starting with '0' became 7-digit numbers starting with '71', making way for subsequent change of the New Territories prefix from '12' to '0'.
- 0xxxxx became 71xxxxx
Fixed-line phone numbers were either six- or seven-digit in the 1980s. Area codes were assigned with the following pattern.
- 3 Kowloon, New Kowloon and Sai Kung
- 5 Hong Kong Island and Outlying Islands
- 0 New Territories
Cellular phone numbers are all eight-digit starting with '9'.
Read more about this topic: Telephone Numbers In Hong Kong