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What is IP Telephony Service?

  • The Internet Protocol (IP) Telephony Service, or Voice over Internet Protocol (VoIP) service, allows users to make or receive telephone calls using a broadband Internet connection instead of a conventional telephone line.
  • As illustrated below, users can make an IP Telephony call through broadband connection to another person using the conventional telephone network or IP Telephony Service, and vice versa.
    IP Phone

What are Class 1 and Class 2 IP Telephony Services?

  • There are two classes of IP Telephony Service in Hong Kong, namely "Class 1 service" and "Class 2 service".
    • Class 1 service is IP Telephony Service that essentially has all the attributes of the conventional telephone service. Telephone numbers under Class 1 service have eight digits and have the number "2" or "3" as prefix(es) for fixed IP Telephony Service, and the number “4”, "5(1-7,9)", "6", “7”, "8” or "9" as prefix(es) for mobile IP Telephony Service, which are similar to the numbers for conventional telephone service.
    • Class 2 service is IP Telephony Service that does not have all the attributes of conventional telephone service (e.g. not necessarily assigned with telephone numbers). When assigned, telephone numbers under Class 2 service also have eight digits but they have "58" as their prefix to distinguish them from Class 1 service. Furthermore, providers of Class 2 service assigned with telephone numbers must declare that their IP Telephony Service is a Class 2 service.
  • Class 2 service providers are not obliged to provide:
    • Number portability - users switching from the conventional phone service or Class 1 IP Telephony Service to Class 2 IP Telephony Service will have to use either new telephone numbers or no number at all as they cannot use their current numbers. Likewise, Class 2 service users switching to any other service providers (including other Class 2 service providers) cannot keep their current numbers.
    • Telephone directory enquiry service – while providers of Class 2 service assigned with telephone numbers are not obliged to provide telephone directory enquiry service, they may choose to do so on a voluntary basis.

What service features are Class 1 and Class 2 service providers obliged to supply to customers in common?

The two service providers are obliged to:

  • Provide access to free emergency service to users of their IP Telephony Services assigned with telephone numbers, and
  • Provide backup power supply to "lifeline device" users if IP Telephony Services are offered to them.

General Advice to IP Telephony Service Users

Number portability

  • Number portability is supported by Class 1 service only but not by Class 2 service. In other words, you can keep your current telephone number when you switch from conventional telephone service to Class 1 service, and vice versa. Your current telephone number can remain the same even if you switch between different service providers of Class 1 service.
  • You cannot keep your current telephone number if you switch from conventional telephone service or Class 1 service to Class 2 service. Likewise, users of Class 2 services assigned with telephone numbers switching to any other service providers (including other Class 2 service providers) cannot keep their current numbers.

Backup power supply

  • Unlike the conventional telephone service, of which electric power is supplied over the telephone line, the equipment that are installed at the customers' premises to support IP Telephony Service such as broadband modems, IP phones, adaptors, and computers all rely on electric power to run.
  • Before you subscribe to an IP Telephony Service, please check with the service provider whether it will provide backup power supply to your telephone set and other related equipment at your premises.
  • For users of "lifeline devices", they should not subscribe to services that do not provide backup power supply.
  • Users of fixed IP Telephony Service are advised to keep a mobile phone for communication during power blackout.

Access to emergency services

  • When you make an emergency call, your call location is a critical piece of information. IP Telephony service providers are required to provide the means for you to update your location whenever you move with your IP Telephony devices. You should check the availability of this service with your service provider. You should also update your location immediately after you have moved.

Quality of service

  • IP Telephony calls are delivered partially or completely over the Internet. The service quality may be beyond the control of the IP Telephony service provider concerned. You should check with your service provider to find out in detail the quality of its IP Telephony Service.

More tips

  • Some IP Telephony service providers offer service packages at very attractive prices. Some service plans allow users to make long distance calls free of charge. You should always clarify with your service provider whether there are restrictions on free long distance calls, whether paid calls are charged on a flat rate or call duration basis, and whether there is a concession period during the day.
  • Before committing to a telecommunications service contract, you should carefully study the information described in any leaflets/advertisements/application form/service contract about the service. You should check whether you are required to sign a fixed term service contract which will bind you to the service for a fixed period of time. This is important because during the term of contract, if for whatever reasons you wish to cancel the contract, you may have to bear a penalty or not be able to get a refund of the money that you have already paid to the service provider. This may happen because some IP Telephony service providers can only provide their services using the service platforms of certain broadband service providers. Also, you will have a problem if during the term of contract you have to move to a new apartment at a location that is not served by these broadband service providers.
  • You have to assess whether there is a possibility that one of your family members may need the "lifeline" service later. If yes, you will need to confirm the availability of backup power supply with the service provider before signing a fixed term contract.
  • The telephone services offered by the existing fixed network operators are no longer limited to conventional telephone service. They may also provide either Class 1 or Class 2 IP Telephony Service. Always check with the service providers on the types of telephone service that they offer.
  • To facilitate heat dissipation and ensure safe operation, an IP phone adaptor and a broadband modem should not be placed on top of each other.