Pegmatite veins, which can form sheets, lenses, or pipes, are often several hundred meters thick and several kilometers long and can be traced at depths of more than 1 km. They occur in clusters that usually cover an area of up to tens of km 2 and that contain from several tens of individual veins to several thousand.
What is a digital telephone line? A digital telephone line or digital trunk is a type of telephone line that carries voice and/or data by using digital sampling.1 vs. PRI. PRI divides a T1 digital signal into 24 channels of 64 Kbps capacity per channel. 23 of these channels can be assigned as one telephone call each, the equivalent of having 23 separate telephone lines. The 24th channel is used for signaling information and special features such as caller ID.
The first phones using digital communication, known as 2G phones, appeared in the early 1990s. Digital phone technology developed rapidly after that. The first text message was sent in 1993, and the transmission of other digital content, such as ringtones and advertising, followed shortly after.