PRI (Primary Rate Interface) consists of 23 B channels and one D channel of 64 Kbps with common throughput of equal dedicated lines throughput of a type 1 meets to 1,544 Mbps in USA. In Europe consists of 30 B channels and one D channel 64 Kbps and corresponds to the channel E1 equal to 2,048 Mbps. Is intended for business clients and represents it (?) as alternative to leased lines, as gives comparable throughput and quality of a signal, but has the greater flexibility.
The advantages of ISDN consist in: bandwidth on demand, opportunity to transfer on one channel voice traffic, and on another the data traffic, and also in view of economy, as for dedicated lines it is necessary to pay without dependence from whether that they are used or not.
As ISDN uses standard wiring to POP, the equipment is necessary only on the ends of a line. To telephone with 2wire line (refers to U) the NT1 device (network termination 1) joins, which is given in usage in Europe and Japan by provider and remains in providers property. In USA, the task of purchase NT1 lays on the consumer. This device transforms signals for communication on 4 wires to the interface S/T, used by the terminal equipment (equipment, which directly establishes connection)
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