PRI is the standard for providing telecommunication services to offices. It is based on the T-carrier (T1) line in the US and Canada, and the E-carrier (E1) line in Europe. The T1 line consists of 24 channels, while an E1 has 32.
■ T1 PRI card with a DSX1 electrical interface supporting 23 bearer channels and
one signaling channel (23B+D). The T1 interface is used in Japan and North
■ E1 PRI card with a G.703 electrical interface supporting 30 bearer channels and
one signaling channel (30B+D). The E1 interface is used outside of Japan and