ISDN-TRK (DS1 ISDN Trunk)

Last Updated : Sep 13, 2023 |

MO name in log

Alarm level

Initial command to run

Full name of MO

ISDN-TRK

MAJ 1

MIN

test port location long

DS1 ISDN Trunk

WRN

test port location
Note:

Many trunk problems are caused by incorrect settings of parameters on the trunk group administration screen. Settings must be compatible with the local environment and with parameter settings on the far end. See Administering Avaya Aura® Communication Manager. Refer to your Avaya representative for the correct settings for administrable timers and other parameters on a country-by-country basis.

For additional repair information, see also DS1 Interface Media Module (MG-DS1) for Media Module ports.

A DS1 ISDN trunk is a 64-kbps bearer channel used to transmit digitized voice or data traffic. These trunks, or B-Channels, use a separate channel, the D-Channel for call-control signaling. This mode of operation is known as out-of-band signaling, as opposed to in-band robbed-bit signaling, in which signaling is carried in the same channel as the voice or data traffic. One D-Channel, or ISDN signaling link (ISDN-PLK), carries signaling messages for several B-Channels, forming an ISDN signaling group (ISDN-SGR).

A B-Channel is a port on a DS1 Interface Media Module.

Two types of DS1 interfaces exist:

  • 24 DS0 channels on a 1.544-Mbps link

  • 31 DS0 channels + 1 framing channel on a 2.048-Mbps link

On 24-channel interfaces, any of the first 23 ports on the DS1 circuit packs or media modules can be a B-Channel. On DS1 Media Module, the 24th port may be used as a B-Channel or as a D-Channel depending on the type of ISDN-PRI signaling group (FAS or NFAS) implemented on the media module. For more details, see ISDN-PRI Signaling Group (ISDN-SGR ).

On 32-channel interfaces, any of ports 1 – 15 and 17 – 31 on the DS1 interface media module can be a B-Channel. The 16th port may be used as a B-Channel or as a D-Channel depending on the type of ISDN-PRI signaling group (FAS or NFAS) to which it belongs. For more details, see ISDN-PRI Signaling Group (ISDN-SGR) and DS1 Interface Media Module (MG-DS1).

For interfaces using country protocol 1 on the DS1 media module administration form (including US), the signaling protocol used for the maintenance of the B-Channel is defined by the Avaya ISDN-PRI specification. For interfaces using country protocols other than 1, the signaling protocol used for the maintenance of the B-Channel is defined by the CCITT ISDN-PRI Specification.

There are five possible service states for a B-Channel. The service state is negotiated with the far-end switch, changes over time, and may have far-end and near-end components. The service state is initialized to Out-of-Service/Far-End, and an attempt is made to negotiate it to In-Service.

Note:

The service state of a particular DS1 ISDN Trunk B-Channel can be displayed by entering status trunk grp#/mem# on the system access terminal.

When a call is present, the specification defines the permissible call states, as well. There are tests in the short and long test sequences for DS1 ISDN Trunk designed to audit these states and ensure agreement between both ends of the PRI connection.

1

A MAJOR alarm on a trunk indicates that alarms on these trunks are not downgraded by the set options.