For any enquiry regarding phone or telecom in general, see with the Office of the Telecommunications
Authority:
Tel: 2961 6333
Web site: www.ofta.gov.hk/
You have different providers but here is the biggest:
Pacific Century Cyberworks Limited (PCCW Ltd)
39/F PCCW Tower, Taikoo Place, 979 King's Road, Quarry Bay, Hong Kong
Tel: 1000 or 2888 2888
24 hour sales hotline: 2888 0008
Website: www.pccw.com/eng/
All fixed line calls within Hong Kong are free. For all services to open an account, a Hong-Kong ID card or passport and proof of residence are necessary. Bills are sent monthly.
Here are some other providers you may want to check out: