iDLU VoIP Gateway for upgrade DLU EWSD

Upgrade and migration of digital line units DLUs EWSD switching system into VoIP Network


  • Provides Connection of EWSD DLUs
  • Supports Measuring of Subscriber Line Parameters
  • Supports SS7, DSS1, V5.2
  • Supports SIP-T, SIP-I
  • voice codecs G.711, G.723, G.726, G.729
  • fax over G.711, T.38 fax relay


Terratel iDLU Media Gateway is designed for migration digital line units DLU subscriber stativs of EWSD system into NGN/IMS next generation networks and upgrade them so that they could be used as a full-featured SS7 Telephone Exchange or subscriber remote node.

Terratel iDLU Gateway will keep existing subscribers, save your investments, reduce operating costs and provide new features of the next generation networks.

iDLU Media Gateway for upgrade and migration DLU EWSD to VoIP Connection Block Diagram

Pic 1. iDLU Gateway Connection Block Diagram.

Access media gateways make it possible to migrate EWSD subscriber equipment to next-generation networks (NGN / IMS) or reconstruct an existing TDM network with minimal investment.

Brief technical specification

  • Up to 3712 POTS for DLU-G
  • Up to 1920 POTS for DLU-B/DLU-D
  • Up to 952 POTS for DLU-A
  • Up to 16 E1 interfaces
  • Up to 480 VoIP channels
  • Support of signaling and protocols SIP, SIP-I, SIP-T, interface DLU, SS7, DSS1, V5.2
  • Dimensions: 1U height, 19″ height for mounting into a telecommunications rack or stative
  • Support of one/two power sources 220 VAC or 48/60 VDC

Connection and migration of existing subscribers of EWSD switching system to multiservice NGN communication networks via DLU

iDLU Media Gateway access without significant installation and commissioning work allows for a radical reconstruction of the switching system EWSD.

As a result, all existing subscribers through the integration of subscriber cabinets DLU and iDLU Media Gateway are serviced by the SoftSwitch.

Network diagram for upgrade DLU EWSD to IP network, NGN multiservice networks

Pic 2. Network scheme for integrating DLU into NGN multiservice communication networks.

Solution features:

  • No need to replace the access equipment (DLU, ISDN PRI, V5.x)
  • Operating concurrently in TDM and VoIP networks
  • Numbering plan is kept fully the same
  • Measurement of parameters of a subscriber line

Reuse HW EWSD to update TDM network

iDLU Media Gateway allows the Operator to reuse the subscriber cabinets of the DLU EWSD digital switching system as a terminal PBX with SS7 signaling system or subscriber removal.

Converting DLU Stative to Telephone Exchange or Subscriber Remote Node

Pic 3. Converting DLU to Terminal Telephone Exchange or Subscriber Remote Node.

Solution features:

  • Converting subscriber extension or DLU stative to full-fledged PBX
  • Support for an existing numbering plan
  • Measurement of subscriber line parameters

Measurement of subscriber line parameters

To measure the parameters of the subscriber line, a measurement module is used, which is a software tool.

The module for measuring subscriber line parameters is fully adapted with standard DLU EWSD commands, which allows you to emulate (replace) line test PC (LT-PC) operation.

A software module models an interface that is equivalent to a subscriber line.

Data and commands for testing and measurement are entered through the Telnet interface.

The following types of measurements are possible:

  • insulation resistance measurement (for A/G, B/G)
  • loop resistance measurement (for A/B)
  • capacitance measurement (for A/G, B/G, A/B)
  • stray voltage measurement (for DC, AC, A/G, B/G, A/B)
The result of the measurements and tests of the subscriber DLU EWSD line

Pic 4. The result of the measurements and tests of the subscriber line.

The result of measurements and tests is reduced to a summary table (Pic 4.), where:

  • DC – constant voltage
  • AC – alternating voltages
  • R – resistance
  • C – capacity
  • A/B – values ​​between wires A and B
  • A/G – values ​​between wire A and ground
  • B/G – values ​​between wire B and ground

Operators can invoke the available commands by entering the relevant data (all parameters related to this command are displayed in the “work window”).

Benefits of Proposed Solution

Terratel iDLU Gateways allow to migrate the EWSD subscriber equipment to the next generation networks (NGN/IMS) or modify the existing TDM network with minimum investments.

It will save your infrastructure costs by using traditional TDM network and facilitate quick deployment of VoIP services which will help to increase revenue opportunities.

Since Terratel iDLU media Gateways support SS7, ISDN PRI and V5.2 protocols they provide for flexible deployment and connection of other TDM systems.

iDLU VoIP Gateway Technical Specifications

Network Interfaces
TDM up to 16 E1 links
SIP and RTP up to 480 VoIP channels, 10/100 BASE-T Ethernet
Management Fast Ethernet, RS-232
Signaling Protocols
Feature Support
Voice codecs G.711, G.723.1, G.726, G.729a/b, GSM
FAX fax over G.711, T.38 fax relay
Echo Cancellation G.165, G.168
Registration and Authentication up to 5000 SIP-subscribers
Registration SIP-trunks
Single/Dual-redundant 220 VAC or/and 48/60 VDC Input
Up to 28W Power consumption
Operations Management
GUI via Embedded Web Server
SNMPv2 monitoring
Syslog Telnet (for CLI)
Integrated firewall, Password protected access, SSH, RADIUS login
Operating Environment
Operating temperature from 0°С to +60°СHumidity
Humidity up to 80% at +25°С
System Type Board
Dimensions 1U high, 19″ wide rack mountable