Primary Rate Interface

The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple DS0 voice and data transmissions between the network and a user.

The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).

The T1 line consists of 23 bearer (B) channels and one data (D) channel for control purposes, for a total bandwidth of 24x64-kbit/s or 1.544 Mbit/s.

The term is applied primarily in relation to the ISDN access interfaces (PRA or PRI and BRA or BRI), since deeper in the PSTN network an ISDN bearer channel is essentially indistinguishable from any other bearer channel.

The T1 line consists of 23 bearer (B) channels and one data (D) channel for control purposes, for a total bandwidth of 24x64-kbit/s or 1.544 Mbit/s.

The bit rate of the D channel of a basic rate interface is 16 kbit/s, whereas it amounts to 64 kbit/s on a primary rate interface.

In contrast to the BRI, the Primary Rate Interface (PRI) configuration provides more B channels and operates at a higher bit rate.

Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).

PRI channels and direct inward dialing are also common as a means of delivering inbound calls to voice over IP gateways from the PSTN.

Nowadays, it is far more common to deliver DID service on a Primary Rate Interface (PRI) circuit.

Caller ID spoofing has been available for years to people with a specialized digital connection to the telephone company, called an ISDN PRI circuit.

The Primary Rate Interface channels are typically used by medium to large enterprises with digital private branch exchange (PBX) telephone systems to provide digital access to the public switched telephone network (PSTN).

The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple DS0 voice and data transmissions between the network and a user.

The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple DS0 voice and data transmissions between the network and a user.

It is based on T-carrier (T1) transmission in the US, Canada, and Japan, while the E-carrier (E1) is common in Europe and Australia.

It is based on T-carrier (T1) transmission in the US, Canada, and Japan, while the E-carrier (E1) is common in Europe and Australia.

The first timeslot on the E1 is used for synchronization purposes and is not considered to be a B- or D-channel.

The Primary Rate Interface channels are typically used by medium to large enterprises with digital private branch exchange (PBX) telephone systems to provide digital access to the public switched telephone network (PSTN).

PRI channels and direct inward dialing are also common as a means of delivering inbound calls to voice over IP gateways from the PSTN.

It holds a pool of 2000 PRIs handling a daily traffic of over 50 million voice calls.

In the typical telephony environment, a PBX connects to the local service provider through Primary Rate Interface (PRI) trunks.

This definition is far below the primary rate interface lower limit defined by the International Telecommunications Union in ITU-R F.1399.

It runs on Linux and requires an E1 interface (ISDN Primary Rate Interface, via mISDN).

These documents, called NET3 for BRI and NET5 for PRI lines, described a set of protocol tests terminals should comply to.

In 1988 the CCITT standards body defined "broadband service" as requiring transmission channels capable of supporting bit rates greater than the primary rate which ranged from about 1.5 to 2 Mbit/s.

Other models can support T1, E1, and ISDN PRI interfaces to provide connections to the PSTN.