S interface

S interface (also known as S0): For basic rate access in an Integrated Services Digital Network (ISDN) environment, a User–network interface reference point that

• (a) is characterized by a Four-wire circuit, 144 kbit/s (2B+D) user rate,
• (b) serves as a universal interface between ISDN terminals or terminal adapters and the network channel termination,
• (c) allows a variety of terminal types and subscriber networks, such as PBXs, local area networks (LANs), and controllers, to be connected to the network, and
• (d) operates at 4000 48 bit frames per second, i.e., 192 kbit/s, with a user portion of 36 bits per frame, i.e., 144 kbit/s.

References

•  This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C"., Entry "S interface"