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Voice Security Recorder


This document describes the features and capabilities of the NEC Dterm Voice Security Recorder (Dterm VSR) and the associated Desktop software solution.

The Dterm VSR consists of a USB device that taps across the digital extension pair of a Dterm Digital extension port and software that enables the user to manage their stored calls.

Advantages Of Digital Recording

The advantages of Digital Recording over analog ‘handset tap’ devices are clear:

  • Higher quality recording
  • Separate channel recording (send/receive) is possible
  • Automatic start/stop of recording when phone is in use
  • Association of caller ID or other call related information (release 2)
  • Doesn’t tie up a PC sound card
  • Easy plug n’ play installation (via USB)
  • Speakerphone conversations can be recorded


The diagram below shows the connection configuration of the Dterm VSR device and the local desktop PC.

The Dterm VSR hardware simply connects in-line at the telephone user’s desktop. No power is required and because the in-line connection is simply a metallic wiring of the ‘in’ and ‘out’ connections, Xtension Recorder does not affect the telephone operation in any way with or without connection of the host PC via USB.

The USB Device

This section describes the NEC Dterm VSR USB device hardware specification. The device is constructed in a UL94 V-0 black polymer and measures 84mm x 72mm x 25mm (or 3” x 2 3/4 ” x 1”).

Device Connections

The VSR device has 3 connectors:

  • One PC USB connector, from which the device derives its power and streams all speech and control channel information up to the host PC and the Desktop software application.
  • Two Digital Phone line connectors that passively ‘tap’ across the Dterm digital connection and ‘listen’ in high impedance mode to the signalling on the line.

Device Performance

The device does not interfere with the communication between the NEC phone system and the Dterm telephone. The device does not require USB power or a connection to the PC to maintain the functionality of the telephone in its normal manner.

The device meets the appropriate FCC and UL requirements required for this type of communications device.

Device Firmware

The device is ‘soft up-loadable’, its firmware is uploaded from the PC driver and Desktop Software application at runtime. This allows for easy upgrade and enhancement of the product in the field as required.

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