AT&T 7100 series, 7500 series System 75/G1 Administration, Comm Type, Group Type, DS1 Options

TRUNKING 1-41

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DMI — A DS1 link that uses the digital multiplexed interface (DMI) as the level 2 protocol on the bearer or information channels.

AVD — When a trunk is administered as AVD, it can carry only voice and digital data. Without explicitly administering the trunk as AVD, only voice and voice-grade data are allowed. This is so if modem pooling is required in the link, the analog/digital transformations will be both accurate and consistent.

System 75/G1 Administration

On System 75 and G1, you specify the trunk type, comm type, and group type at the Trunk Group screen.

Trunk Type

At the Trunk Group screen, in the trunk type field, you specify the type of signaling protocol the trunk will use. (For an explanation of the signaling protocol see System 85/G2 Administration, above.) See the DEFINITY Communications System, Generic 1.1 Implementation manual, 555-204-654, for further details.

Comm Type

In the comm type field, you can specify a trunk as voice, data, avd (for alternating voice and data), or rbavd (for robbed bit avd). Some Software-Defined Network (SDN) implementations require trunks groups to be administered as rbavd. See the DEFINITY Communications System, Generic 1.1 Implementation manual, 555-204-654, for further details. For further details on the comm type rbavd, see appendix G.

Group Type

You also enter the group type at the Trunk Group screen. Group types can be "tie," "tandem," "ISDN PRI," and so forth. See the DEFINITY Communications System, Generic 1.1 Implementation manual, 555-204-654, for further details.

DS1 Options

When you access either the LEC or the interexchange carrier through a digital trunk, the kind of route you choose for access may be through restricted or unrestricted channels, or through multiplexing equipment (like a D4 channel bank). The characteristics of the route will dictate:

∙Line coding (ZCS or B8ZS)

∙Framing (D4 or ESF)

∙Signaling (robbed-bit or 24th-channel)

See the Multiplexed Communication section of this chapter for an explanation of each of these options.

DS1 options are administered as follows:

∙Line coding — On System 85 and G2, you can administer a DS1 port for either ZCS or B8ZS line coding through PROC 260, field 9. On System 75 and G1, use the DS1 Circuit Pack Screen to set these options.