Direct inward dial

direct inward dialingDIDdirect inbound dialing
To allow public switched telephone network (PSTN) users to directly reach users with VoIP phones, DID numbers are assigned to a communications gateway. The gateway connects the PSTN to the VoIP network, routing and translating calls between the two networks. In countries with multiple competing local providers, DID services can be purchased in bulk from a Competitive Local Exchange Carrier (CLEC). For voice over IP resellers, some specialized CLECs (for local numbers) or interexchange carriers (for toll-free numbers) will deliver blocks of direct inward dial calls already converted to Session Initiation Protocol (SIP) or common VoIP formats.

Asterisk (PBX)

AsteriskAsterisk PBXHigh Availability for Asterisk
In conjunction with suitable telephony hardware interfaces and network applications, Asterisk is used to establish and control telephone calls between telecommunication endpoints, such as customary telephone sets, destinations on the public switched telephone network (PSTN), and devices or services on voice over Internet Protocol (VoIP) networks. Its name comes from the asterisk symbol for a signal used in dual-tone multi-frequency (DTMF) dialing. Asterisk was created in 1999 by Mark Spencer of Digium, today a division of Sangoma Technologies Corporation.

Enhanced 9-1-1

E911enhanced 911Wireless Enhanced 911
The dispatcher's computer uses information provided by the telephone company to display the physical address or geographic coordinates of the caller. This information is used to dispatch police, fire, medical, and other services as needed. Calls to 911 over the public switched telephone network (PSTN) are routed to a special router (known as Selective Router, or 9-1-1 Tandem). The router looks for the address associated with the caller's telephone number in a database. The caller's phone number is known as an ANI. The database relating ANIs to addresses is known as ALI (Automatic Location Identification).

Intelligent Network

INIntelligent Network (IN)IN platform
It is intended for fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing value-added services in addition to the standard telecom services such as PSTN, ISDN on fixed networks, and GSM services on mobile phones or other mobile devices. The intelligence is provided by network nodes on the service layer, distinct from the switching layer of the core network, as opposed to solutions based on intelligence in the core switches or equipment. The IN nodes are typically owned by telecommunications service providers such as a telephone company or mobile phone operator.

Automated attendant

auto attendantauto-attendantphone tree
Modern AA services (which now overlap with more complicated interactive voice response or IVR systems) can route calls to mobile phones, VoIP virtual phones, other AAs/IVRs, or other locations using traditional land-line phones. Telephone callers will recognize an automated attendant system as one that greets calls incoming to an organization with a recorded greeting of the form, "Thank you for calling .... If you know your party's extension, you may dial it any time during this message." Callers who have a touch tone (DTMF) phone can dial an extension number or, in most cases, wait for operator ("attendant") assistance.

Sampling (signal processing)

sampling ratesamplingsample rate
For most phonemes, almost all of the energy is contained in the 100 Hz–4 kHz range, allowing a sampling rate of 8 kHz. This is the sampling rate used by nearly all telephony systems, which use the G.711 sampling and quantization specifications. Standard-definition television (SDTV) uses either 720 by 480 pixels (US NTSC 525-line) or 704 by 576 pixels (UK PAL 625-line) for the visible picture area. High-definition television (HDTV) uses 720p (progressive), 1080i (interlaced), and 1080p (progressive, also known as Full-HD). In digital video, the temporal sampling rate is defined the frame rate or rather the field rate rather than the notional pixel clock.

History of the telephone

telephonemechanical telephonetelephone history
Internet Protocol (IP) telephony, also known as Internet telephony or Voice over Internet Protocol (VoIP), is a disruptive technology that is rapidly gaining ground against traditional telephone network technologies. In Japan and South Korea up to 10% of subscribers switched to this type of telephone service as of January 2005. IP telephony uses a broadband Internet service to transmit conversations as data packets. In addition to replacing the traditional plain old telephone service (POTS) systems, IP telephony also competes with mobile phone networks by offering free or lower cost service via WiFi hotspots.

Number pooling

North American mobile telephones, from their introduction in 1983, have used local numbers from the same geographic area codes as wireline services. Unlike the system in nations where mobiles have their own special area code, the recipient of a mobile call in the US or Canada pays the airtime charges. In most areas, one carrier held a monopoly on local service. The landline telephone system was originally constructed in an era before transistorisation, remote concentrators or cabinetisation. Individual lines from subscribers ran not to a remote concentrator but directly to the nearest village community dial office, to be terminated at an automated mechanical switch or manual exchange.

History of videotelephony

We were certain that such a device would make cell phone communications much more convenient and enjoyable." Saburi also stated that their R&D section had "nourished [the idea] for several years before" they received project approval from their top management which had encourage such forward-thinking research, because they "also believed that such a product would improve Kyocera's brand image." Their research showed that a "cell phone with a camera and color display provided a completely new value for users, It could be used as a phone, a camera and a photo album".

Trillium Digital Systems

TrilliumProduct HistoryTrillium Digital Systems, Inc.
Trillium software products were used in communications and networking products designed for the PDN, PSTN, Internet, enterprise networks and home networks. Trillium's evolution and development, paralleled the evolution and development of the communications industry. In 1988 there were less than 1/2 million Internet users, about 4 million cell phone users and no broadband (DSL, cable) users. The industry went through significant transitions from the mid-1980s through the early 2000s, as described in the market history section. By 2008 there were over 1.4 billion Internet users, almost 3.3 billion mobile phone users and over 1 billion broadband users.

VoIP spam

SPIT (SPam over Internet Telephony)SPIT
Robocalls can be delivered automatically using telephony software, such as Asterisk. RFC 5039 contains some basic methods for the mitigation of telephony spam over SIP: A strong identification of the caller, for example as described in RFC 4474 helps to mitigate SPIT. In a Public switched telephone network (PSTN), the Caller ID permits caller identification, but at least the displayed caller ID can be spoofed. Various SPIT mitigation methods and frameworks have been proposed. The vast amount of work on spam detection in emails does not directly apply here because of the real-time nature of the voice calls.

Telephone prefix

prefixdialing prefixphone prefix
eo:Telefonprefikso Telephone numbering plan. List of international call prefixes. List of country calling codes.

Dial tone

dial-tonedialling tonestutter dial tone
A dial tone is a telephony signal sent by a telephone exchange or private branch exchange (PBX) to a terminating device, such as a telephone, when an off-hook condition is detected. It indicates that the exchange is working and is ready to initiate a telephone call. The tone stops when the first dialed digit is recognized. If no digits are forthcoming, the permanent signal procedure is invoked, often eliciting a special information tone and an intercept message, followed by the off-hook tone, requiring the caller to hang up and redial. Early telephone exchanges signaled the switchboard operator when a subscriber picked up the telephone handset to make a call.

Timeline of the telephone

chronicles the developmentexistence of a transatlantic telephoneon-or-off transmission methods
the United States. 8 December 1937: Opening of fourth transcontinental telephone line. 1941: Multi-frequency dialing introduced for operators in Baltimore, Maryland. 1942: Telephone production is halted at Western Electric until 1945 for civilian distribution due to the retooling of factories for military equipment during World War II. 1946: National Numbering Plan (area codes). 1946: first commercial mobile phone call. 1946: Bell Labs develops the germanium point-contact transistor. 1947: December, W.

Global network

globalglobally distributed networkglobal networks
Telephony. Fiber optic cable. Telegraphy.

Telephone network

Network engineeringtelephonefixed and mobile networks
A telephone network is a telecommunications network used for telephone calls between two or more parties. There are a number of different types of telephone network: Public telephone operators (PTOs) own and build networks of the first two types and provide services to the public under license from the national government. Virtual Network Operators (VNOs) lease capacity wholesale from the PTOs and sell on telephony service to the public directly * Telephone service (disambiguation) A landline network where the telephones must be directly wired into a single telephone exchange. This is known as the public switched telephone network or PSTN.

Nepal Telecom

It has a total of 262 telephone exchanges in various parts of the country serving 603,291 PSTN lines, more than 5 million GSM cellular phones and more than a million CDMA phone line as of July 2011. According to recent data, there are about 10 million users of Nepal Telecom including all those of fixed landline, GSM mobile, CDMA and internet service. Nepal Telecom Launched 4G LTE Service on 1 January 2017.

Telecommunications in India

TelephonecommunicationsIndian Telecom Industry
However, after a number of proactive initiatives taken by regulators and licensors, the total number of mobile subscribers has increased rapidly to over 929 million subscribers as of May 2012. In March 2008, the total GSM and CDMA mobile subscriber base in the country was 375 million, which represented a nearly 50% growth when compared with previous year. As the unbranded Chinese cell phones which do not have International Mobile Equipment Identity (IMEI) numbers pose a serious security risk to the country, Mobile network operators therefore suspended the usage of around 30 million mobile phones (about 8% of all mobiles in the country) by 30 April 2009.

Call Control eXtensible Markup Language

Combines CCXML, VoiceXML with MRCP, HTTP(s) interfaces and connects to internet protocol, fixed telephony and mobile phone telecoms networks using SIP, VOIP, SS7/PSTN and other telecoms protocols. Supports multi-tenant applications. Open Source Oktopous PIK an abstract, C++ implementation of the W3C Call Control XML (ccXML) standard. Licensed under a BSD-Style license, the toolkit is independent of the underlying telephony platform / protocols and is best suited for OEM / System Integrators looking to implement ccXML functionality in their product offerings. Originally developed by Phonologies, Oktopous has been adopted by more telephony platforms than any open source ccXML Browser.


On April 28, 2008 Jajah provideds its proprietary telephony infrastructure, payment processing, and customer care to Yahoo! Messenger users using the platform for receiving calls from the PSTN network, or for making calls to land lines and mobile phones. Telefónica bought Jajah for a reported $207 million on December 23, 2009. On April 14, 2011, Jajah announced a partnership with Globe Telecom to allow Filipinos living outside Philippines to call home at inexpensive rate. It announced November 30, 2012 that effective January 30, 2013, Yahoo! Messenger will no longer offer Yahoo! Voice Phone In and Phone Out capabilities, the co-branded landline and mobile phone service from Jajah.

History of telecommunication

enormously increased speed of telecommunicationshistory of telecommunicationsprogress
The first and historically most important application for communication satellites was in intercontinental long distance telephony. The fixed Public Switched Telephone Network relays telephone calls from land line telephones to an earth station, where they are then transmitted a receiving satellite dish via a geostationary satellite in Earth orbit. Improvements in submarine communications cables, through the use of fiber-optics, caused some decline in the use of satellites for fixed telephony in the late 20th century, but they still exclusively service remote islands such as Ascension Island, Saint Helena, Diego Garcia, and Easter Island, where no submarine cables are in service.

Foreign exchange service (telecommunications)

foreign exchange officeforeign exchange stationforeign exchange
These are commonly found in devices acting as gateways between local Voice over Internet Protocol (VoIP) systems and the public switched telephone network (PSTN). In a nutshell, an FXO device is any device that, from the point of view of a telephone exchange, appears to be a regular telephone. As such, it should be able to accept ringing signals, go on-hook and off-hook, and send and receive voice frequency signals. It may use loop start or ground start signaling. FXO channel units were invented and named in the middle 20th century for service at the "Office" end of an FX line via carrier system.

Telecommunications relay service

7-1-1captioned telephone711
Most IP relay services support many types of technologies, such as Web browser, mobile phone app, text messaging, WAP, instant messaging, and Text over IP (ToIP). Support for many technologies has made it possible to use almost any generic connected device to use a relay service, such as a personal computer, laptop, mobile phone, PDA, or other device capable of utilizing the connection methods provided by an IP relay provider. Video relay service (VRS) allows people who use sign language to place phone calls by signing instead of typing.


modemsdial-up modem56k modem
The WiFi and WiMax standards use wireless mobile broadband modems operating at microwave frequencies. Modems which use a mobile telephone system (GPRS, UMTS, HSPA, EVDO, WiMax, etc.), are known as mobile broadband modems (sometimes also called wireless modems). Wireless modems can be embedded inside a laptop or appliance, or be external to it. External wireless modems are connect cards, USB modems for mobile broadband and cellular routers. A connect card is a PC Card or ExpressCard which slides into a PCMCIA/PC card/ExpressCard slot on a computer. USB wireless modems use a USB port on the laptop instead of a PC card or ExpressCard slot.

Cellular network

cellularmobile networkcellular networks
., mobile phones, tablets and laptops equipped with mobile broadband modems, pagers, etc.) to communicate with each other and with fixed transceivers and telephones anywhere in the network, via base stations, even if some of the transceivers are moving through more than one cell during transmission. Cellular networks offer a number of desirable features: Major telecommunications providers have deployed voice and data cellular networks over most of the inhabited land area of Earth. This allows mobile phones and mobile computing devices to be connected to the public switched telephone network and public Internet.