Key Telecommunications Services [Telecom]

Telecommunications services can be divided into three key categories;
- voice
- data
- and video.

Each of these categories has specific characteristics such as maximum transmission delay time, minimum and maximum transmission rates, and acceptable transmission error types and rates.

Voice services involves receiving of audio signals, processing audio signals into various formats (analog and digital), storing and transporting these signals, and converting the signals back into a form that is similar to its original form. The characteristics of voice networks are very small transmission delay (below 100 msec typical), maximum of 64 kbps for each digital voice channel, and reasonable tolerance to errors. Examples of voice services are Telephony, Voice Messaging, Call Processing, and Computer and Telephony Integration, CTI.

Data services provide transport of digital information from one point to one or more points. The characteristics of data networks are moderate transmission delays (above 1 sec may be acceptable), minimum of 28 kbps for each dial-up digital customer and 1 Mbps for each broadband customer, and very low tolerance to errors. Examples of data services include switched connections (circuit switched channels / dial-up, dedicated lines (leased lines/circuits), packet switching (e.g. Internet), and multicast and broadcast (one to many) data transfer.

Video services transport high information content signals (video) from one point to one or more points. The characteristics of video networks are very long transmission delay (above 15 seconds for digital broadcast acceptable), minimum of 1 Mbps for each digital video channel (3.2 Mbps for DVD), and reasonable tolerance to errors. Examples of video services include television, closed circuit TV (CCTV), video on demand (VOD), videoconferencing, and interactive multimedia.

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