This is specifically attractive for video conference codex and hi-fi sound. 2.048 Mbps - using 5 H0 channels. H12 - at 1.920 Mbps. H22 - around 54 Mbps. H4 - around 135 Mbps.
Higher rate interfaces Optical fibers offer virtually unlimited bandwidth.
There are still some technical and economic problems in providing these services to customers, but these problems can undoubtedly be overcome. For example, if it is unacceptable to use one fiber per connection, then wavelength division multiplexing offers enormous capacity. The concept of ISDN is that there should be a minimum number of interfaces identified so that a wide range of compatible equipment should be available. That means that channel rates like those that have been specified above would not cause the creation of interfaces by the customer operating. So far only 2 interfaces have been identified - the basic rate interface and primary rate interface.