Public utility

utilitiespublic utilitiesutility
The term utilities can also refer to the set of services provided by these organizations consumed by the public: Coal, electricity, natural gas, water, sewage, telephone, and transportation. Broadband internet services (both fixed-line and mobile) are increasingly being included within the definition. In the United States, public utilities are often natural monopolies because the infrastructure required to produce and deliver a product such as electricity or water is very expensive to build and maintain. As a result, they are often government monopolies, or if privately owned, the sectors are specially regulated by a public utilities commission.

Bell System

BellBell Operating CompaniesBell Telephone
American Telephone and Telegraph Company, a holding company and long-distance carrier. Illinois Bell Telephone Company. Indiana Bell Telephone Company, Incorporated. Michigan Bell Telephone Company. New England Telephone and Telegraph Company. New Jersey Bell Telephone Company. New York Telephone Company. Northwestern Bell Telephone Company. Pacific Northwest Bell Telephone Company. South Central Bell Telephone Company. Southern Bell Telephone and Telegraph Company. Southwestern Bell Telephone Company. The Bell Telephone Company of Pennsylvania. The Chesapeake and Potomac Telephone Company. The Chesapeake and Potomac Telephone Company of Maryland.

Fiber to the x

FTTHfiber to the homefibre to the home
For FTTC and FTTN, the combined internet, video and telephone signal travels to the building over existing telephone or cable wiring until it reaches the end-user's living space, where a VDSL or DOCSIS modem converts data and video signals into ethernet protocol, which is sent over the end-user's category 5 cable. *National broadband plans from around the world de:Glasfasernetz de:Fiber In The Loop FTTP (fiber-to-the-premises): This term is used either as a blanket term for both FTTH and FTTB, or where the fiber network includes both homes and small businesses. FTTH (fiber-to-the-home): Fiber reaches the boundary of the living space, such as a box on the outside wall of a home.

Bell Labs

Bell Telephone LaboratoriesBell LaboratoriesAT&T Bell Laboratories
History of mobile phones—Bell Laboratories conception and development of cellular phones. High speed photography & Wollensak—Fastax high speed (rotating prism) cameras developed by Bell Labs. Knolls Atomic Power Laboratory. Simplified Message Desk Interface. Sound film—Westrex sound system for cinema films developed by Bell Labs. TWX Magazine—A short-lived trade periodical published by Bell Laboratories (1944–1952). Walter A. Shewhart—Bell Laboratories engineer—"father of statistical quality control". "Worse is Better"—A software design philosophy also called "The New Jersey Style" under which UNIX and C were supposedly developed.


onlinethe Internetweb
Internet telephony is another common communications service made possible by the creation of the Internet. VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underlies all Internet communication. The idea began in the early 1990s with walkie-talkie-like voice applications for personal computers. In recent years many VoIP systems have become as easy to use and as convenient as a normal telephone. The benefit is that, as the Internet carries the voice traffic, VoIP can be free or cost much less than a traditional telephone call, especially over long distances and especially for those with always-on Internet connections such as cable or ADSL and mobile data.

Digital Signal 1

DS1 is the primary digital telephone standard used in the United States, Canada and Japan and is able to transmit up to 24 multiplexed voice and data calls over telephone lines. E-carrier is used in place of T-carrier outside the United States, Canada, Japan, and South Korea. DS1 is the logical bit pattern used over a physical T1 line; in practice, the terms "DS1" and "T1" are often used interchangeably. T1 refers to the primary digital telephone carrier system used in North America. T1 is one line type of the PCM T-carrier hierarchy.


T1T-1T1 carrier
The T-carriers are commonly used for trunking between switching centers in a telephone network, including to private branch exchange (PBX) interconnect points. It uses the same twisted pair copper wire that analog trunks used, employing one pair for transmitting, and another pair for receiving. Signal repeaters may be used for extended distance requirements. Before the digital T-carrier system, carrier wave systems such as 12-channel carrier systems worked by frequency division multiplexing; each call was an analog signal. A T1 trunk could transmit 24 telephone calls at a time, because it used a digital carrier signal called Digital Signal 1 (DS-1).


E1E-1digital trunks
Nonblocking minimal spanning switch - discussion of practical telephone switches. Clos network - the mathematics of telephone switches.

Synchronous optical networking

Local "craftspersons" (telephone network engineers) can access a SDH/ SONET network element on a "craft port" and issue commands through a dumb terminal or terminal emulation program running on a laptop. This interface can also be attached to a console server, allowing for remote out-of-band management and logging. TL1 Electrical interface. The electrical interface, often a 50-ohm coaxial cable, sends SONET TL1 commands from a local management network physically housed in the central office where the SONET network element is located. This is for local management of that network element and, possibly, remote management of other SONET network elements.

Audio engineer

engineeringengineersound engineer
Ensuring speech is transmitted intelligibly, efficiently and with high quality; in rooms, through public address systems and through mobile telephone systems are important areas of study. A variety of terms are used to describe audio engineers who install or operate sound recording, sound reinforcement, or sound broadcasting equipment, including large and small format consoles. Terms such as "audio technician," "sound technician," "audio engineer," "audio technologist," "recording engineer," "sound mixer" and "sound engineer" can be ambiguous; depending on the context they may be synonymous, or they may refer to different roles in audio production.

Mobile Telephone Service

MTSLimited capacity Mobile Telephone Service for automobilesMobile Service
The Mobile Telephone Service (MTS) was a pre-cellular VHF radio system that linked to the Public Switched Telephone Network (PSTN). MTS was the radiotelephone equivalent of land dial phone service. The Mobile Telephone Service was one of the earliest mobile telephone standards. It was operator assisted in both directions, meaning that if one were called from a land line the call would be routed to a mobile operator, who would route it to one's phone. Similarly, to make an outbound call one had to go through the mobile operator, who would ask for the mobile number and the number to be called, and would then place the call.

On- and Off-hook

off-hookon-hookon hook
In telephony, on-hook and off-hook refer to the two possible states of a receiver. Off-hook originally referred to the condition that prevailed when telephones had a separate earpiece (i.e., receiver), which hung from its switchhook until the user wished to activate it. The weight of the receiver no longer depresses the spring-loaded switchhook, thereby connecting the instrument to the telephone line. The term off-hook has the following meanings: On an ordinary two-wire telephone line, off-hook status is communicated to the telephone exchange by a resistance short across the pair.

Telecommunications in Brazil

Other areas of the country, particularly the North and Northeast regions, lack even basic analog PSTN telephone lines. This is a problem that the government is trying to solve by linking the liberation of new technologies such as WiMax and FTTH) only tied with compromises on extension of the service to less populated regions. The Brazilian landline sector is fully open to competition and continues to attract operators. The bulk of the market is divided between four operators: Telefónica, América Móvil, Oi (controlled by Brazilian investors and Portugal Telecom), and GVT.

Multi-frequency signaling

Benefits include higher connection establishment rate, better fraud security and features such as Caller ID Some 911 Public Safety Answering Points (PSAPs) still use the MF format to identify the calling party to the PSAP when processing calls from Mobile Telephone Switching Offices (MTSOs) and land telephone offices. This is based on an earlier system which used MF to identify the calling party to a feature group 'D' (101xxxx) alternate long distance provider. Other countries may still use a version of in-band signaling.


5G NR5th generation mobile networks3GPP 5G New Radio (NR) standards,
List of mobile phone generations (1G, 2G, 3G, 3.5G, 4G, 4.5G, 5G). Network simulation. Next Generation Mobile Networks (NGMN) Alliance.

Telecommunications in Syria

International dialing code: +963 Landline telephones in use in 2009: 4,069,000. Mobile phones in use in 2009: 11,696,000. The mobile operators are Syriatel ( and MTN ( There is mobile phone coverage in most parts of Syria providing access to 96% of the population. Call quality ranges from Good to acceptable. Many international calls fail or are less clear over the mobile network compared to the landline network. Radio: 14 AM, 11 FM, and 1 shortwave stations in 1998. The radio operators are the state owned Syrian Arab Republic Radio and Al-Madina FM, the first private radio station, launched in March 2005.

Packet switching

packet-switched networkpacket-switchedpacket switched
Newer mobile phone technologies (e.g., GPRS, i-mode) also use packet switching. X.25 is a notable use of packet switching in that, despite being based on packet switching methods, it provides virtual circuits to the user. These virtual circuits carry variable-length packets. In 1978, X.25 provided the first international and commercial packet switching network, the International Packet Switched Service (IPSS). Asynchronous Transfer Mode (ATM) also is a virtual circuit technology, which uses fixed-length cell relay connection oriented packet switching. Datagram packet switching is also called connectionless networking because no connections are established.

Public land mobile network

PLMNmobile phone network
Mobile phones use this to detect Roaming, so that a mobile phone subscribed on a network with a PLMN code that mismatches the start of the USIM's IMSI will typically display an "R" on the icon that indicates connection strength. A PLMN typically offers the following services to a mobile subscriber: The availability, quality and bandwidth of these services strongly depends on the particular technology used to implement a PLMN. Location Area Identity (LAI) (PLMN and Location Area Code). Cell Global Identity (CGI) (LAI and Cell Identifier). IMSI (see PLMN code and IMSI). Emergency calls to local Fire/Ambulance/Police stations.