Under licence conditions, PCCW-HKT Telephone Limited and Hong Kong Telecommunications (HKT) Limited has a USO, under which, basic services should be made reasonably available to all persons in Hong Kong, at service charges capped by the published tariffs. The USO mainly covers basic fixed voice telephony services and public payphones. Broadband or mobile services are not covered under the USO, and the coverage of such services is mainly a commercial decision.
As for other fixed network operators, their service coverage is basically a commercial decision. That said, all fixed network operators are required under their licence conditions to provide service upon request of a customer if their networks have already been rolled out to the location concerned. Please contact the fixed network operators directly for details about the service coverage. Their contact numbers can be found in "Choices of Service Providers"