ISDN Description

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.

ISDN Standards Information

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}

ISDN IC Manufacturers

AKM Semiconductor {Codec / Transceiver IC for ISDN}

Cologne Chip {ISDN controllers}

CML Microcircuits

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).

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Modified 6/13/15
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