Digital Subscriber Signalling System No. 1 (DSS1) is a

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

signalling protocol (D channel protocol) used for the

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. ...

. It is defined by ITU-T I.411 (ETS 300 102Integrated Services Digital Network (ISDN); User-network interface layer 3 Specifications for basic call control
/ref>). It supports

Bearer Capability Bearer Capability in telecommunications is one of the Information Elements (fields) of the Q.931 SETUP message. It is used by the calling party to specify the type of B channel being requested. Description For example, if a Bearer Capability of Sp ...

, Low Level Compatibility and High Level Compatibility, ANI, DNIS and redirected number signaling in both directions. A standard developed by

ETSI The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of Information and communications technology, information and communications. ETSI supports the de ...

for

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

is known as Euro-ISDN or E-DSS1 or simply EDSS1 (European DSS1). DSS1/EDSS1 protocol, in contrast, for example, to the protocol

QSIG QSIG is an ISDN based signaling protocol for signaling between private branch exchanges (PBXs) in a private integrated services network (PISN). It makes use of the connection-level Q.931 protocol and the application-level ROSE protocol. ISDN "p ...

, was designed for use as access to public

and asymmetric in the sense that it suggests a link with the network side at one end (digital public telephone exchange) and the user (

private branch exchange A business telephone system is a telephone system typically used in business environments, encompassing the range of technology from the key telephone system (KTS) to the private branch exchange (PBX). A business telephone system differs from ...

(PBX)) - at the other. Since the market for ISDN equipment was open, ETSI provided guidance to suppliers of ISDN equipment by means of the minimum requirements for inter-connectivity to ISDN networks. These documents, called NET3 for BRI and NET5 for PRI lines, described a set of protocol tests terminals should comply to. Later, testing institutes, like

KEMA Kema or KEMA may refer to: * KEMA, an energy consultancy company * Kema (river), a river in Russia * Kema District, a district in North Sulawesi, Indonesia * Kema Chikwe, Nigerian politician * Kema Jack (born 1982), footballer from Papua New Guinea ...

in the Netherlands, implemented and performed the protocol tests and provided the appropriate certificates. In 1989, 26 network operators from 20 European countries decided to develop EDSS1 as a pan-

an standard to replace earlier national protocols (such as FTZ 1 TR 6 (Germany) or VN3 (France)). EDSS1 has been one of the keys to the success of the

within European countries (as compared to, for example, the

U.S. The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous ...

). Non-European countries using DSS1 include

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Singapore Singapore, officially the Republic of Singapore, is an island country and city-state in Southeast Asia. The country's territory comprises one main island, 63 satellite islands and islets, and one outlying islet. It is about one degree ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

Palestine Palestine, officially the State of Palestine, is a country in West Asia. Recognized by International recognition of Palestine, 147 of the UN's 193 member states, it encompasses the Israeli-occupied West Bank, including East Jerusalem, and th ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, and the

United Arab Emirates The United Arab Emirates (UAE), or simply the Emirates, is a country in West Asia, in the Middle East, at the eastern end of the Arabian Peninsula. It is a Federal monarchy, federal elective monarchy made up of Emirates of the United Arab E ...

. The DSS1 protocol knows four different codesets for information elements. Codeset 0 regards to Q.931, Codeset 5 to the ETSI standard, Codeset 6 for national applications and Codeset 7 for PBX applications. The most common Codeset is 0/Q.931.

References

{{reflist Integrated Services Digital Network