Primary Rate Interface (PRI) has 23 B (bearer) channels and one D (data) channel in United States, Canada, and some Caribbean islands (all places with a country code of 1). In the rest of the world, a PRI uses 30 B channels and one D channel. These are usually known as the 23B+D and 30B+D formats.
Each B channel carries a 64 kbps timeslot (data or voice).
The D channel is also a 64 kbps timeslot, carrying signaling for all the B channels. On a 23B+D PRI, the D channel is found in channel 23. On a 30B+D PRI, it is in channel 15.
Digital calls over a B channel are handled by the ISDN processor in the router, and analog modem calls are handled by the on-board modems in the router.
Basic Rate Interface (BRI) has two B channels and one D channel. Each B channel is 64 kbps, and the D channel is 16 kbps, for a total of 144 kbps. This is known as the 2B+D format.
BRI interfaces can use a service profile identifier (SPID) number for identification. It is assigned by the service provider.
1. | Set the global ISDN switch type for all PRI interfaces:
(global) isdn switch-type switch-type
The ISDN switch-type must be set to match the switching equipment being used by the telephony provider. In North America, use basic-5ess (Lucent basic rate switches), basic-dms100 (NT DMS-100 basic rate switches), or basic-ni1 (National ISDN-1). In Australia, use basic-ts013 (TS013). In Europe, use basic-1tr6 (German 1TR6), basic-nwnet3 (Norwegian NET3 phase 1), basic-net3 (NET3), vn2 (French VN2), or vn3 (French VN3). In Japan, use ntt (NTT). In New Zealand, use basic-nznet3 (New Zealand NET3).
Note
To use QSIG signaling, use a switch-type of basic-qsig.
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2. | Configure the T1/E1 controller.
- a. Select the controller:
(global) controller {t1 | e1} slot/port
-or-
(global) card type {t1 | e1} slot
A T1/E1 controller is referenced by controller and slot and port number on 2600 and 3600 routers and by card type and slot number on 7200, 7500, and AS5x00 routers and access servers.
- b. (Optional) Set the ISDN switch type for this PRI:
(global) isdn switch-type switch-type
The switch type can also be set on a per-PRI basis, overriding the global switch type.
- c. Set the framing type:
(controller) framing {sf | esf | crc4 | no-crc4} [australia]
The T1 framing type can be sf (super frame, the default) or esf (extended super frame). The E1 framing type can be crc4 (the default), no-crc4, and an optional australia.
- d. Set the clock source:
(controller) clock source {line [primary | secondary] | internal}
The controller can derive its clock from line (CO or external source) or internal (the controller’s internal clock). A line clock can be designated as primary (preferred over other controllers’ line clocks) or secondary (used as a backup external clock source).
- e. Set the line encoding:
(controller) linecode {ami | b8zs | hdb3}
For a T1, the line coding can be set to ami (the default) or b8zs (binary 8 zero substitution). For an E1, it can be set to ami or hdb3 (the default; high-densitybipolar 3).
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3. | Configure the PRI group:
(controller) pri-group [timeslots range]
The voice timeslots are identified as a range (numbers 1 to 23 or 1 to 30, separated by a dash or comma). If the timeslots and range keywords are not used, the default is a PRI with 23 B channels and one D channel.
Note
To reference the serial interfaces corresponding to the PRI channels, use interface serial controller:channel, where controller is the T1 controller number for the physical connection and channel is 0 to 22 for B channels 1 to 23 and 23 for the D channel. (Interface channel numbering begins at 0, and T1/E1 channel numbering begins at 1.) For an E1 controller, the channel is 0 to 30 for B channels and 15 for the D channel.
When you are configuring a PRI for dial-related features, always configure the features on the D channel.
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4. | (Optional) Set the B channel ordering for outgoing calls.
- a. Select the D channel interface:
(global) interface serial controller:[23 | 15]
The D channel is identified as channel 23 for a T1 PRI and channel 15 for an E1 PRI.
- b. Set the order:
(interface) isdn bchan-number-order {ascending | descending}
The first available B channel can begin with B1 in ascending order or B23/B30 in descending order (the default). Make sure the order used matches that of your service provider.
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5. | Set other optional parameters.
- a. (Optional) Use TEI negotiation:
(interface) isdn tei [first-call | powerup]
By default, TEI negotiation occurs when the router is powered up (powerup). In Europe or when connecting to a DMS-100 ISDN switch, you might need to perform the negotiation during the first active call (first-call).
- b. (Optional) Send a calling number with outbound calls:
(interface) isdn calling-number calling-number
The calling-number (a string of digits) represents a telephone number to be used as a billing number by the service provider.
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