What Is ISDN?:
The letters stand for; "Integrated Services Data Network" and, frankly, it's antiquated technology! It was originally developed as a high speed internet connection for use, primarily, by businesses. With the development of newer technology such as FIOS, ISDN has been replaced by faster ways to access the web. However, ISDN lives on because of its unique ability to combine bearer channels ("b" channels), increasing speed and bandwidth. This enables the transmission of much larger chunks of data at speeds that allow the real-time transfer of high quality audio and video.
ISDN phone lines are much more expensive than regular telephone lines, and the hardware needed to encode and decode the audio at each end is also pretty pricey. But, in audio recording studios, it became the ultimate solution for the constant demand for quick turn-around.
The general public probably first became aware of the use of ISDN for remote audio recording with the release of Frank Sinatra's famous "Duet's" album in 1993. He recorded duets with several other famous artists, such as U2's Bono and Aretha Franklin. The media got wind of the fact that his fellow performers were almost never actually in the same studio with him. It was ISDN that enabled them to record together, without anyone having to travel. Gloria Estifan and Old Blue Eyes sang "Come Rain Or Come Shine" for the album, but Gloria was in Miami and Frank was in Las Vegas.
Yes, the quality is that good! Today ISDN remains the industry standard for remote audio recording, and Joe's studio features a top-of-the-line codec which is put to good use several times a week. Other technology is knocking on the door, hoping to replace ISDN (which the phone companies would like to retire in the next few years), but it hasn't gotten to the point where lower operating costs and initial investment make up for their lack of stability and occasional problems caused by internet data traffic jams.