ISDN [Integrated Services Digital Network] is a communication standard
for sending Voice, Video, and Data over digital or analog telephone
lines. Basic Rate (BRI) ISDN consists of two 64-Kbps B-channels and one
D-channel for transmitting control information. Primary Rate ISDN
consists of 23 B-channels and one D-channel [U.S.] or 30 B-channels and
one D-channel [Europe]. The ISDN 64kps rate is based on sampling analog
voice lines at 8000 times per second with 8 bits per sample. The 64Kbps
channels are called B channels. The 16Kbps channels are called D
channels. ISDN is a switched, end-to-end network that allows for
simultaneous transmission. With two full duplex digital channels, Basic
Rate Interface (BRI) ISDN provides high-speed. 128 kilobits per second
(kbps) is typical, up to 512kbps with compression. Primary Rate Interface
(PRI) ISDN bundles twenty-three channels together, to provide speeds of
up to 1,544 kbps.
The transmission speeds above also relate back to the DS0 and T1 data
rates and are described here for completeness. The voice signal is
sampled at a 8kHz rate and digitized into 8 bits producing 64kbps per
separate phone line. The 64kbps speed is defined as DS0 [Digital Signal
0]. When 24 DS0s are combined together the result is DS1 [T1]. T1 lines
are formed when 24 digitized phone lines are combined into a single
digital data stream. The resulting data stream has a rate of 1.544Mbps
[24 * 64,000 = 1.536Mbps plus a framing bit]. The T1 data stream is Time
Division Multiplexed [TDM] by channel; 8 bits [one sample] of channel 1
followed by 8 bits of channel 2 and so on. T1 trunks are bi-direction,
one twisted pair for transmit and one twisted pair for receive. The
frames consists of one 8 bit sample for each of the 24 channels, or 24
[channels] x 8 [data bits] + 8 bit [frame] = 193 bits. Then 193 bits x 8K
samples = 1.544 Mbps.
Primary Rate Interface (PRI): An integrated services digital network (ISDN) interface standard (a) that is designated in North America as having a 23B+D channels, (b) in which all circuit-switched B channels operate at 64 kb/s, and (c) in which the D channel also operates at 64 kb/s. Note: The PRI combination of channels results in a digital signal 1 (T1) interface at the network boundary.
E-series - Overall network operation
E.100-199 Definitions and general provisions regarding telephony
service
E.700-749 ISDN Traffic Engineering
E.800-855 QOS
G-series - Transmission systems and media, digital systems and
networks
G.700-709 Digital transmission systems
G.711-728 PCM coding
G.960-969 Digital section and digital transmission systems for
customer access to ISDN
ITU; {International Telecommunication Union}
AKM Semiconductor {Codec / Transceiver IC for ISDN}
Cologne Chip {ISDN controllers}
Maxim {T1/E1 IC Manufacturer}
Infineon {ISDN - DDA - T1 ICs}
PMC-Sierra Inc. {T1/E1}
STMicroelectronics {ISDN ICs}
Texas Instruments 'TI'
TranSwitch Corp. {DS3 - T1 Interface ICs}
Telecom Device Manufacturers {Digital / Specialized Logic}
Or Integrated Circuit IC Manufacturers {All other
functions}
Inductor Manufacturers
{all frequency ranges}
U interface: For basic-rate access in an Integrated Services Digital Network (ISDN) environment, a user-to-network interface reference point that is characterized by the use of a 2-wire-loop transmission system that (a) conveys information between the 4-wire user-to-network interface, i.e., the S/T reference point, and the local exchange, (b) is located in the servicing central office, and (c) is not as distance sensitive as a service using a T interface.
Signaling System No. 7 (SS7): A common-channel
signaling system defined by the CCITT in the 1988 Blue Book, in Recommendations Q.771 through Q.774.
Note: SS7 is a prerequisite for implementation of an Integrated Services Digital Network (ISDN).
{Back to ISDN Manufacturers Index}
Home | |||||||
Distributors | Components | Equipment | Software | Standards | Buses | Design | Reference |