GSB is a joint venture between the city's leading terrestrial player, Television Broadcasts (TVB) and global satellite service provider Intelsat.
Its exTV is an all-digital service providing 23 channels, which will be going up against PCCW's Now Broadband TV, also with 23 channels which launched last September, and the long-established Cable TV, which has an offering of more than 70 channels.
The new service, which has been under a trial run in more than 130,000 households since the beginning of this year, is transmitted to homes via satellite and set-top boxes.
Jim Blomfield, exTV CEO, said the company's core mission was to provide "viewers with an interesting range of programming".
However, media planners said the market was beginning to become satuarated, especially since Cable TV is planning to increase its offering to over 100 channels in the near future.
OMD Hong Kong general manager Jackson Kwok described Hong Kong as being too small for more than two players. The newcomers would find it especially difficult in terms of distribution and programme acquisition.