The ULSB MK III Switch


Matrix Military PBX – ETERNITY MEX is the highly integrated unit level switch board (ULSB MK III) built to match the critical criteria of military communication systems. The universal interfaces, non-blocking architecture, redundant configuration, ruggedized and toughened structure and adherence to all stringent military standards deliver the dependable performance.

ETERNITY MEX main switch encompasses the system processing, power supply and various network and extension cards in a modular architecture. The exchange offers connectivity to various trunks and subscribers in form of plug-in cards. Due to the universal personality of the slots an interface card can be flexibly inserted in any of the vacant slot. Built-in redundancy of power supply and CPU facilitate uninterrupted operation-24x7.

The integrated exchange offers interfaces for POTS, E&M, LD, ISDN BRI and E1/PRI. On the extensions side the switch supports analog extensions, magneto phones and digital subscribers.The switch offers direct termination for voice and data delivered over copper or optic fibre networks. A data card facilitates data transfer and control applications with integrated 4 Ethernet ports. A bifurcated E1 stream can be mapped to any Ethernet port. Software configurable for CAS, R2MFC, PRI and QSIG, the switch offers transparent networking between the telephone exchanges.

The informative operator console, accessories, camouflage packaging and mounting kit facilitates the operation and transportation in rough terrain conditions. The specially designed Military PBX guarantees that troops communicate faster and more securely even in challenging conditions. The Power-on-Self-Test (POST), On-line and Off-line diagnosis of cards, Built-in Test Equipment (BITE) of various ports ensures the simple installation, easy troubleshooting and quick maintenance for minimum downtime.

The cautious approach in designing, right from mounting modules on cards to the outermost casing, makes ETERNITY MEX extremely light-weight and compact.

Operator Console

  • 4x40 VFD Display
  • Status Indicators
  • Ringer Lamp and Buzzer for Call Indication
  • Programmable Direct Access Function Keys
  • Dedicated Call Management and 4-way Navigation Keys
  • MIL Standard Headset and Handset Connector

Features & Functions

MEX functions as an automated call management exchange, flexibly managing calls right from initiation to termination. The intelligent exchange seamlessly routes calls between various network ports, from trunks to subscriber stations and amongst the various subscriber stations. Multi-location networking can be done over ISDN, E1 or E&M lines, extending system features and capacity till a distant comrade unit.

Incoming calls can be automatically directed to specific users; else routed amongst a group of users as per pre-defined priorities. Outgoing calls are routed via the most-cost-effective network calculating various algorithms. The dial plans can be unlike for different groups and flexibly revived as per the time of calling.

ETERNITY MEX delivers intelligent features to its service extensions, such as remembering access codes for easy and speed dialing, forwarding calls to desired extension, grouping extensions, establishing conferencing circuits for multi-party conversations, re-attempting calls at unsuccessful trials and many others. ETERNITY MEX logs all its activity, maintains a detailed call activity reports with the provision to back-up and print the same.


An indispensible requirement of a military exchange is to perform and perform at every instant. The envisaged military environment is highly strenuous for any equipment. Ruggedized to tolerate all the duress, MEX is engineered to offer a reliable performance under all arduous situations. The distributed processing architecture with local processing units for each card localize fault points and lead to fault isolation and easier fault identification. Integrated DSP based SLIC and DAA are used for analog subscriber and trunk Interfaces along with automatic thermal management on subscriber and tie lines.

On-board secondary protection, over voltage and current protection eliminate overheating or breakdowns. The LTB also comes with 5-Stage protection. The MTBF is better than 5000 working hours with a repair time less than 30 minutes.

1+1 Hot-Standby for critical cards offers true redundancy. In the event of failure of the active card, the changeover to the standby card is automatic and transparent, without any disruption of services. All the interface cards are hot­-swappable, eliminating unhealthy system down-time.

Network Management (MMI)

MEX configuration is possible from subscriber stations, operator console as well as via a local/remote terminal. Ruggedized network management terminal/MMI with user friendly web based GUI allows the switch to be configured, monitored and managed remotely. The system access can be secured with passwords differentiated for access at various levels. The switch also provides a MIL standard MMI interface on the front fascia with an EMI protected cable with a sealed connector on one end and industrial standard connector for laptop.

System Traffic and Statistics

Comprehensive monitoring and management reports can be generated with per port/trunk occupation details. Built-in SMDR for 12000 records is provided. System Event and Fault Logs can also be generated for easier troubleshooting and maintenance. These logs can also be viewed on the VFD display of operator console.

Testing and Evaluation

Besides the network management terminal, card level system diagnosis is available through the LED status indicators on the operator console and the corresponding textual messages displayed on the VFD. Power-on self-test (POST), on-line and off-line diagnostics offer self-diagnosis of various cards. Built-in Test Equipment (BITE) testing of various ports like SLT, Magneto, CO (TWT), E&M and LD can also be done.


(MIL STD-461D and JSS-55555)
MEX is well armored at each and every step of its designing. Housed in a ruggedized cabinet, the connectors and MDF are duly toughened. There are no moving parts and cards are well secured to the slots. MEX is ruggedized to match all the specifications as per table L2B of JSS-55555. Abiding the EMI/EMC specifications as per MIL STD-461D ensure impervious performance under varying climatic conditions. Draped in a color scheme in camouflage to the field environment, MEX is built to endure extreme variations of temperature, pressure and humidity. The ruggedization offers absolute endurance against vibration, shock, bounce, collision, drop, duress, dust and immersion.


The military exchange is destined to be installed in harsh locations, to be carried on rough and bumpy terrains. It may be carried physically, in cars and trucks and also in aircrafts. All the handheld devices along with the unit level switch are easily portable and light weight. The accessories include transit-case and harnesses for the switch (main unit), LTB, FCBC, batteries and laptop. The light-weight switch, with all the accessories is ideal for carriage as man-pack equipment and for vehicular transport. An appropriate vehicle mounting arrangement is provided to mount the switch and FCBC which can be then mounted on the platform of wheeled vehicle.


Handset and Headset

Handset and Headset

  • Rugged handset and headset
  • Retractable coiled cord and standard termination of the handset
  • Superior voice quality

Line Termination Box (LTB)

  • The LTB connects telephone lines coming from outside
  • The LTB offers terminations for BRI, E1/PRI, analog phones,
    magneto junctions, CO ports, LD and E&M ports
  • Five stage protection module
  • Integrated protection against lightning, electrical surges and
    standing voltages for each port
  • Suitable case and harness for easy transit.

Float Cum Boost Charger (FCBC)

  • FCBC Input: 150-300 VAC
  • Battery Output: 48 VDC
  • FCBC Output: 48VDC to ULSB Power Supply Card
  • Built-in Battery Charging Circuit
  • Auto Change-over from AC to DC and Vice-Versa
  • Over Voltage and Reverse Voltage Protection
  • Low Battery Cut-off
  • 1+1 Redundancy of SMPS
  • LED Indication: power supply failure, battery fault, low battery,
    battery under/over voltage conditions, reverse battery condition,
    float of charging mode

Vehicle Mounting Kit (VMK/VIK)

The frequent movement of equipment's is a regular activity for armed
forces due to changes in operation locations and regimes as per the
changing tactics. The Main Switch unit and FCBC come with a vehicle mounting.


  • Earthing Spikes, Earthing Rods, Cables and Braid
  • Field type of Earthing (up to 5 ohm)
  • Earthing points on Main Switch, FCBC and LTB

Float Cum Boost Charger (FCBC)

Line Termination Box (LTB)

Vehicle Mounting Kit (VMK/VIK)



System Specifications:

Type of Switching PCM/TDM Digital Switching (100% Non-blocking)
Processor 32-bit RISC
Architecture Distributed Processing

System Capacity and Resources:

Total Port Capacity 184
Total Slots 12
Universal Slots 8
RS232C (COM) Port 1
USB Port 1

Power Supply:

Input 48VDC (+/- 20%) Operation
FCBC Input: 150V to 300V AC Operation
Battery Output: 48V DC,
Battery Backup with Built-in Charging Circuit
Auto Change-over from AC to DC


MEX Unit Weight: 19.460 Kg
Dimension (WxHxD): 39.3 x 23 x 51.5 cm
FCBC Weight: 5.180 Kg
Dimension (WxHxD): 39.7 x 6.8 x 31.4 cm
LTB Weight: 11.260 Kg
Dimension (WxHxD): 47.2 x 10 x 37.6 cm


Environmental Standards As per JSS 55555 (L2B Table)
Literature As per JSS 0251-01



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