Primary Rate Interface (PRI)

In DSX-80/160, PRI provides for connection to advanced digital lines and simplifies installation.
  • PRI requires T1/PRI PCB P/N 1091006.
  • Expanded CPN per extension is available in software versions 3.01 or higher. This allows the system to send a unique 10-digit telephone number to the called party for each extension.
Additional Feature Information
Direct Inward Dialing
T1 Lines
Programming for this Feature
Programming PRI Basics
Programming Incoming Calling Party Number and Name
Programming Outgoing Calling Party Number (CPN)
Programming T1 Lines
Programming Outside Line Type, Access, and Ringing
Programming Caller ID


When a T1/PRI PCB (P/N 1091006) is installed, DSX-80/160 is compatible with ISDN Primary Rate Interface (PRI) circuits that use the NI-2 and DMS-100 signaling types. PRI provides 23 voice channels and a signaling channel (23B+D) in one circuit. Each T1/PRI PCB supports one 23B+D PRI circuit in a single RJ45 connector for a capacity of 23 lines. You can set up each line individually as one of the following line types:
  • Loop Start DTMF
  • DID Immediate Start DTMF

Similar to T1, PRI gives the system the advantages of advanced digital calling as well as conserving PCB slots. For example, you can set up a system with 12 loop start lines and 11 DID lines and use only a single PCB slot. Additionally, the T1/PRI PCB has its own on-board processor and DSP so it minimally impacts other system resources.

Incoming Calling Party Number and Name

If provided by the telco, DSX PRI supports the following incoming Calling Party Number (CPN) options:
  • Calling Party Number
    • The keyset displays the Calling Party Number sent by the telco as the call is ringing. The Calling Party Number can be up to 16 digits long.
  • Calling Party Name
    • As the call rings the keyset displays both the Calling Party Number and the Calling Party Name. The Calling Party Number can be up to 16 digits long and the Calling Party Name can be up to 15 ASCII characters long.

Incoming Calling Party Number is available on Loop Start DTMF and DID Immediate Start DTMF PRI lines when the Caller ID Type is set to T1/PRI.

Outgoing Calling Party Number

The outgoing Calling Party Number (CPN) on a PRI line is provided by interaction of the programming set up for the system telephone number, the PRI line outgoing number, and the extension's outgoing ANI number. Here's how it works:
  1. For PRI calls, the system's outgoing Calling Party Number is initially provided by the system telephone number set in 1011-02: Telephone Number [System: Config: Setup: Name (1011): Phone Number].
  2. If a PRI line has its own outgoing number programmed in 3101-07: Telephone Number [Lines: Config: Setup: Type (3101): Phone Number], the system outputs that number instead.
  3. [3.01] If an extension in turn has outgoing ANI programmed in 2101-05: Outgoing ANI ID [Stations: Config: Setup: Type (2101): ANI ID], the system will use the digits (18 maximum) stored for the extension instead.

Outgoing Calling Party Number Example

Here is an example of how outgoing Calling Party Number over PRI lines can work:
[3.01] For outgoing PRI calls:
  • All outgoing PRI calls (except line 1 and extension 302) use 203 926 5400.
  • All outgoing PRI calls on line 1 (except for extension 302) use 203 926 6400.
  • An outgoing PRI call from extension 302 on any line uses 850 555 1212.

Outgoing Calling Party Number Privacy

An extension’s Class of Service can optionally enable or disable Outgoing Calling Party Number Privacy. When an extension has Privacy enabled, the call recipient should see “Private Number” in their Caller ID display for calls over a PRI line from the extension. If disabled, the call recipient sees the Outgoing Calling Party Number programmed in the system.

Routing on the Dialed Number Received (Direct Inward Dialing)

Direct Inward Dialing (DID) routing for PRI lines is available when:
  • The PRI line receiving the call is set for DID Immediate Start.
  • The connected telco sends the Calling Party Number.
  • The DSX system’s DID programming is set for compatibility with the received Calling Party Number.

Installation Note

Although the T1/PRI PCB can connect directly to the telco’s smart jack, your telco may require that you purchase and install a separate Channel Service Unit (CSU). This unit installs between the smart jack and the T1/PRI PCB.

Conditions and Defaults


  • None.

Default Setting

  • No PRI PCBs programmed.

Other Related Features


  • Central Office Calls, Placing
    • DSX provides individual En-bloc dialing for PRI lines. This makes the operation of PRI transparent to the user. It is not necessary to enable Store and Forward for PRI lines to facilitate En-bloc dialing.
  • Direct Inward Dialing
    • DID service is available on PRI lines.
  • T1 Lines
    • T1 lines give the system a maximum of 24 lines in a single PCB slot.

IntraMail Features

  • None.