The I.431/430 Networking standards are recommendations produced by the
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
. They are
Layer 1 specifications for
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 ...
networks, using either an
E1 or
T1 circuit. The I.431 standard is known as the '
PRI Physical Layer' whereas the
I.430 is known as the '
BRI Physical Layer'.
External links
I.431 : Primary rate user-network interface - Layer 1 specificationfrom the ITU
ITU-T I Series Recommendations
Integrated Services Digital Network