Digital Access Signalling System 1 (DASS1) is a
proprietary protocol defined by
British Telecom to provide
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. ...
services in the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
.
It is now obsolete, having been replaced by
DASS2. This too will become obsolete over the coming years as
Q.931, a European standard, becomes widely adopted in the
EU.
References
BT Group
History of telecommunications in the United Kingdom
Integrated Services Digital Network
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