1.5 Administrator's Guide

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  4. Commissioning the unit
  5. Configuring Comma device ports
  6. Configuring BRI ports

Configuring BRI ports

Field

Content

Link Type

Indicates whether this device is part of a point-to-point (i.e. DIDs may be issued by the telco) or point-to-multipoint (i.e. one or more multi-subscriber numbers may be issued, or multiple BRI devices share the BRI bus.) The link type needs to match the mode of the service provided by the telco.

Act as NT

When disabled, the device is an ISDN TE, connected to the telco NT. When enabled, this port acts as though it is an ISDN NT device. This is useful when the Comma device is placed between the PBX and the telco NT, e.g. for least-cost routing and BRI gateway routing.

Bus termination

Comma BRI cards have terminating resistors on-board, removing the need for external terminators. If this device should terminate the BRI bus (this is the usual case), enable this setting.

If multiple devices are attached to the BRI cable (point-to-multipoint) and another device is providing termination, the Com.X can be configured not to terminate.

A BRI link should always be terminated by a device on at least one side of the BRI connection, or electrical reflection on the link could interfere with BRI signaling and result in loss of layer 1 link establishment, or CRC errors.

Echo canceler

The echo cancellation delay and algorithm to be employed on the port. The delay up to which the echo canceler can compensate is specified in milli-seconds. An optional non-linear processing echo suppression algorithm (NLP) can also be employed during echo cancellation. If you expect the devices connected to the port to be in a noisy environment how-ever, you might prefer not to enable NLP, as it might result in the far-end noise being cut off when speech ceases. Some local users may find this uncomfortable. NLP is recommended for quiet remote environments. Please see section 3.6.8.1 for a detailed discussion around echo cancellation.

Note: This setting applies to all BRI ports in the same BRI trunk group as this BRI port. This option is not available if the port is not part of at least one BRI trunk group.

Detect Fax

When enabled, all BRI ports in all trunk groups to which this BRI port belongs will detect fax tones and disable echo cancellation for the duration of a fax call. We recommend enabling this feature on all BRI ports that are likely to support fax calls.

Note: This option is not available if the port is not part of at least one BRI trunk group.