According to Hongkong Telecom corporate marketing general manager Bernard Fung, Hongkong Telecom ISDN access covers about 90 per cent of the territory including access to Chek Lap Kok airport.

Hongkong Telecom offers access to 34 countries and is committed to offering access to mainland cities.

The operator recently connected to Beijing, Shanghai and Guangzhou. Plans are to have 13 more cities within Guangdong province connected before the end of the year, and most big provinces and cities within a year.

Hongkong Telecom is being challenged by fixed-line operators, especially New T&T which launched an ISDN service last December.

Although they have yet to make official announcements, Hutchison and New World also are set to launch ISDN services in the coming months.

To provide ISDN, New T&T has to rely on Hongkong Telecom's network and has to pay the telecom firm's interconnection fees.

These are judged too high by New T&T. New T&T chairman Leslie Harris said when two networks met, each party should pay its own costs.

Last summer, New T&T complained to the Office for Telecommunications Authority (Ofta) and is still waiting for the authority to rule on the dispute.

There were similar problems concerning co-location agreements, stopping New T&T from providing international connections, Mr Harris said.

This had prevented New T&T from promoting its ISDN services, he said.

While conceding that with 3,000 lines installed since the ISDN service was launched in October last year, there was plenty of room for improvement. Mr Fung said expanded coverage and value-added services would help Hongkong Telecom attract subscribers.

New features Hongkong Telecom has added since the launch include closed user group, a software-based security feature which allows users to register a list of numbers.

Call management services such as call waiting and call forwarding were being developed and would be available in the near future, Mr Fung said.

ISDN connection is ideal for customers who require occasional data transmission such as video-on-demand or leased line backup and is recommended when usage is kept to less than three hours a day.

The bulk of customers are business customers mostly from banking and financial institutions, who use ISDN connections for video-conferencing sessions and backup; internet services providers for host-to-computer connection; and retail shops for POS applications.

Hong Kong's big retailer, 7-Eleven has used ISDN to re-engineer its supply chain process and implement a just-in-time inventory system.

Hongkong Telecom offers two types of ISDN lines: Datapak ISDN2 and Datapak ISDN 23 which deliver data transmission rates of 128 kilobits per second and 1.5 Mbps.