Modem

modemsdial-up modem56k modem
Direct broadcast satellite, WiFi, and mobile phones all use modems to communicate, as do most other wireless services today. Modern telecommunications and data networks also make extensive use of radio modems where long distance data links are required. Such systems are an important part of the PSTN, and are also in common use for high-speed computer network links to outlying areas where fibre is not economical. Even where a cable is installed, it is often possible to get better performance or make other parts of the system simpler by using radio frequencies and modulation techniques through a cable.

History of the telephone

telephonemechanical telephonetelephone history
By the 1990s, telecommunication networks such as the public switched telephone network (PSTN) had been largely digitized with very-large-scale integration (VLSI) CMOS PCM codec-filters, widely used in switching systems for telephone exchanges, private branch exchanges (PBX) and key telephone systems (KTS); user-end modems; data transmission applications such as digital loop carriers, pair gain multiplexers, telephone loop extenders, integrated services digital network (ISDN) terminals, digital cordless telephones and digital cell phones; and applications such as speech recognition equipment, voice data storage, voice mail and digital tapeless answering machines.

Last mile

last-milefinal stagefirst-mile
Examples are the copper wire subscriber lines connecting landline telephones to the local telephone exchange; coaxial cable service drops carrying cable television signals from utility poles to subscribers' homes, and cell towers linking local cell phones to the cellular network. The word "mile" is used metaphorically; the length of the last mile link may be more or less than a mile. Because the last mile of a network to the user is conversely the first mile from the user's premises to the outside world when the user is sending data, the term first mile is also alternatively used.

Automatic number identification

ANIautomatic number identification (ANI)the caller's number
Modern toll-free telephone numbers, which generate itemized billing of all calls received instead of relying on the special fixed-rate trunks of the Bell System's original Inward WATS service, depend on ANI to track inbound calls to numbers in special area codes such as +1-800, 888, 877, 866, 855, 844 with 833 and 822 reserved for future toll free use (United States and Canada), 1800 (Australia) or 0800 and 0808 (United Kingdom). ANI is different, conceptually and technically, from caller ID service. A caller's telephone number and line type are captured by ANI service even if caller ID blocking is activated.

Access network

accessaccess networksOptical Distribution Network
Access is essential to the future profitability of operators who are experiencing massive reductions in revenue from plain old telephone services, due in part to the opening of historically nationalized companies to competition, and in part to increased use of mobile phones and voice over IP (VoIP) services. Operators offered additional services such as xDSL based broadband and IPTV (Internet Protocol Television) to guarantee profit. The access network is again the main barrier to achieving these profits since operators worldwide have accurate records of only 40% to 60% of the network.

Call centre

call centercall centerscall centres
In a virtual call centre model, the call centre operator (business) pays a monthly or annual fee to a vendor that hosts the call centre telephony and data equipment in their own facility - Cloud based. In this model, the operator does not own, operate or host the equipment on which the call centre runs. Agents connect to the vendor's equipment through traditional PSTN telephone lines, or over voice over IP. Calls to and from prospects or contacts originate from or terminate at the vendor's data centre, rather than at the call centre operator's premises. The vendor's telephony equipment (at times data servers) then connects the calls to the call centre operator's agents.

Called party

calleebe calledcall receiver
The called party also pays if the number dialed is a toll-free telephone number. In some countries such as Canada, the United States and China, users of mobile phones pay for the "airtime" to receive calls. In most other countries (e.g. most European countries), the elevated interconnect fees are paid fully by the calling party and the called party incurs no charge. de:B-Teilnehmer

Direct inward dial

Direct Inward Dialingdirect inbound dialingDDI
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.

Satellite phone

satellite telephonesatellite telephonysatellite phones
A satellite telephone, satellite phone or satphone is a type of mobile phone that connects to other phones or the telephone network by radio through orbiting satellites instead of terrestrial cell sites, as cellphones do. The advantage of a satphone is that its use is not limited to areas covered by cell towers; it can be used in most or all geographic locations on the Earth's surface. The mobile equipment, also known as a terminal, varies widely. Early satellite phone handsets had a size and weight comparable to that of a late-1980s or early-1990s mobile phone, but usually with a large retractable antenna.

Enhanced 9-1-1

Enhanced 911E911E-911
The dispatcher's computer receives information from the telephone company about the physical address (for landlines) or geographic coordinates (for wireless) 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).

Telephone prefix

prefixdialing prefixprefixed
A telephone prefix is the first set of digits after the country, and area codes of a telephone number; in the North American Numbering Plan countries (country code +# ), it is the first three digits of a seven-digit phone number, 3-3-4 scheme. In other countries both the prefix and the number may have different lengths. It shows which exchange the remaining numbers refer to. A full telephone number is usually made up of country code (required for international calls only), area code (required for calls between telephone areas), prefix, and subscriber number. Some places restrict certain prefixes to fax numbers or cell phones only; in other places such dedicated prefixes are not used.

Intelligent Network

INAdvanced Intelligent NetworkIntelligent Network (IN)
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. IN is supported by the Signaling System #7 (SS7) protocol between network switching centers and other network nodes owned by network operators.

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.

Cordless telephone

cordless phonecordless phonescordless telephones
Also required is a call management function and a gateway to the public switched telephone network (PSTN). This may or may not be integrated in the base-station. A Voice over IP service can be used by phones that use wireless data access points, thus using a broadband Internet connection to defer the connection to the PSTN to a remote gateway operated by the service provider, close to the call's destination. Analog equivalents do exist and can provide longer reach, but with potential loss of confidentiality and voice quality.

Party line (telephony)

party lineparty linestelephone party line
This system would fail if any provision was made to allow the subscriber to turn off the bells (do not disturb) for privacy or unplug the telephone; it also presumed that each subscriber only had one telephone connected to the line. One variation of identifying the calling party on direct dialed long distance calls is a party code, usually a single digit inside a circle displayed on the phone's number tag. The dialing sequence for such calls is "1" (access number for DDD), the party code, the area code, and the desired number (1 + party code + area code + number).

Number pooling

Widescale introduction of new area codes created confusion as consumers were often unaware which were domestic-rate calls and which were premium calls to Caribbean or foreign numbers within the NANP. The new area codes brought an initial flood of split plans which changed millions of existing numbers. Businesses in the newly created area codes (such as area code 520 in Arizona) found many clients attempting to call them were instead repeatedly reaching a wrong number due to incompatible or misconfigured switching equipment at call origin which could not handle the new codes.

History of videotelephony

Picturephone
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.

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.

Global network

globalglobally distributed networkglobal networks
History of the telephone. History of telegraphy. Mobile telecommunications. Computer networking. Communication protocol. Network architecture. Global network positioning. 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

NTC
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.

Call Control eXtensible Markup Language

CCXML
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.