R interface or R reference point defines the point between a non-
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. Work ...
device and a terminal adapter (TA) which provides translation to and from such a device.
See also
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S interface
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T interface
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U interface
U or u, is the twenty-first and sixth-to-last letter and fifth vowel letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''u'' (pr ...
References
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ITU-T recommendations
Integrated Services Digital Network
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