Integrated Services Digital Network ( ISDN)
Integrated Services Digital Network ( ISDN) is a series of networking protocols for continuous multimedia transmission of voice, video, data, and other network services through the public switched telephone network's conventional circuits. It was first established in the "Red Book" of the CCITT in 1988.[1] Before ISDN, the telephone system was seen as a means of transporting speech, with some special services available for data. ISDN's main advantage is that it incorporates speech and data on the same lines, incorporating functionality not present in the traditional telephone system. ISDN specifications describe various types of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI).
ISDN Products
ISDN ProductsIntegrated services refer to the ability of ISDN to provide at least two simultaneous communications over a single line, in any combination of data, voice, video, and fax. The line can be connected to multiple devices and used as needed. This means an ISDN line will take care of what was supposed to be the full connectivity needs of most people (apart from wireless internet access and entertainment television) at a much higher transmission rate, without having numerous analog telephone lines to purchase. This also applies to integrated switching and transmission[5], in which telephone switching and carrier wave transmission are combined and not separate as in previous technology.
ISDN and broadcast industry
The broadcast industry makes heavy use of ISDN as a secure way to turn low-latency, high-quality, long-distance audio circuits. In combination with a suitable codec using MPEG or the proprietary algorithms of different manufacturers, an ISDN BRI can be used to send bidirectional stereo audio coded at 128 kbit / s with 20 Hz – 20 kHz audio bandwidth, although the G.722 algorithm is widely used with a single 64 kbit / s B channel to send much lower latency mono audio at the cost of audio quality. Where several ISDN BRIs are needed to provide a higher bandwidth circuit switching link in parallel, very high-quality audio may be used. BBC Radio 3 often uses 3 ISDN BRIs.
Consumer and industry perspectives
There is a second point of view: that of the telecommunications market, where ISDN is a central technology. A network of telephones can be viewed as a series of wires strung between switching systems. For the signals on these wires, the common electrical specification is T1 or E1. The signaling is carried out via SS7 between telephone company switches. A PBX is normally connected via a T1 with a robbed bit signal to indicate on-hook or off-hook conditions, and MF and DTMF tones to encode the destination number. ISDN is much easier because messages can be sent much quicker than by attempting to encode numbers as long as the tone sequences (100 ms per digit). Which results in faster setup times for calling.
ISDN and broadcast industry
The broadcast industry makes heavy use of ISDN as a secure way to turn low-latency, high-quality, long-distance audio circuits. In combination with a suitable codec using MPEG or the proprietary algorithms of different manufacturers, an ISDN BRI can be used to send bidirectional stereo audio coded at 128 kbit / s with 20 Hz – 20 kHz audio bandwidth, although the G.722 algorithm is widely used with a single 64 kbit / s B channel to send much lower latency mono audio at the cost of audio quality. Where several ISDN BRIs are needed to provide a higher bandwidth circuit-switched link in parallel, very high-quality audio can be used.
ANUPAM SINGH
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