AT&T System 85 manual Digital Terminal Data Module Dtdm, Block Diagram of Dtdm Interfaces

ISDN Asynchronous Data Module (ADM)

Digital Terminal Data Module (DTDM)

The DTDM provides a DCE interface to a DTE device that is connected to the DTDM (see

Figure 2 below) and allows the DTE to communicate with the switch through the voice terminal and its mounting cord. Data calls and voice calls can be carried on simultaneously, or data calls can be initiated independently of voice calls. The DTDM and the digital voice terminal integrate data and voice into the DCP interface with the system digital switch. The voice terminal user can continue to access all voice features while the module is active on a data call.

Addition of a DTDM allows an in-place 7403D or 7405D voice terminal to be upgraded for data communications at low cost.

FIGURE 5-2. Block Diagram of DTDM Interfaces

Physical Description

The DTDM is contained in a molded plastic housing styled to match the associated voice termi- nal. Status lights, switches, and controls are located on the faceplate and behind a hinged side cover.

Dimensions

Note: The following dimensions are approximate.

Width = 4-3/4 inches

Depth (front to back) = 8-3/4 inches

Thickness = 1-1/2 inches

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