NMS Communication - SS7 Version 3X

Call Control and Messaging Redundancy for Higher Availability

NMS Communications' SS7 Version 3.x software provides Message Transfer Part (MTP), Integrated Services Digital Network User Part (ISUP), Telephone User Part (TUP), Signaling Control Connection Part (SCCP), and Transaction Capabilities Application Part (TCAP) redundancy. Redundancy allows applications to preserve stable calls or message transactions during maintenance upgrades or in the event of board or node failures.


  • Supports the sharing of a single Point Code by redundant MTP, ISUP, SCCP, and TCAP protocol layers
  • Health management interface allows user applications to detect and recover from hardware or software failures
  • Automatic detection and prevention of application message overloads (congestion handling)
  • Off-loads SS7 protocol processing from the host computer to board-based protocol stack
  • Allows cost-effective access to the SS7 network for integration into products from OEMs and infrastructure providers
  • Provides support for both Solaris™ and Windows® system-level operating systems
  • Reduces application development time through NMS' Natural Access™ API interface
  • Provides support for intelligent peripherals, service nodes, and adjunct processor applications
  • Provides underlying protocols required to support higher-layer Mobile Switching Center (MSC) and Base Station Controller (BSC) protocols
  • Compliant with ANSI, ITU-T, and ETSI SS7 standards
  • Provides modular implementation of SS7 protocol stack with host computer Application Programming Interfaces (APIs) to MTP layers 2 and 3, ISUP, SCCP, and TCAP
  • Supports a selection of TX Series network interface configurations including T1, E1, and V.35
  • H.100-, H.110- and MVIP-compliant

Technical Description:

Two Platforms, One Point Code

Carrier-grade systems require extremely high levels of network uptime, typically 99.999%. A critical requirement in many systems is to eliminate single points of failure in SS7 links, SS7 boards, and system chassis. Furthermore, systems require the ability to perform hardware and software upgrades without system downtime. One solution is to use multiple chassis, each with an SS7 board and supporting one or more SS7 links. NMS SS7 Version 3.x allows two TX boards to share the same Point Code such that the remote node sees the pair of boards as a single entity.

The SS7 links and MTP2 are active on both boards. On one board, MTP3, the higher SS7 protocol layers and the user's application can act in a primary (active) mode; on the other board, each layer acts in a secondary (backup) mode. The primary MTP3 passes MTP check-point information, including MTP's routes and link sets, to the backup board. The primary ISUP layer passes SS7 traffic data to the application. The application can check-point the information to the backup ISUP layer. In providing SCCP/TCAP redundancy, these layers perform check-pointing directly between the primary and secondary boards before passing the results to the application.

A fast LAN between a primary and secondary board provides a way for each system to monitor the health and status of each other. In the event of a failure, the back-up board takes over and uses the check-pointed data both to know the current state of the SS7 network and to allow stable calls to remain up. The remote node views the failure of the primary board as it would a simple link failure and is therefore able to automatically handle the board or chassis failure as specified within the SS7 protocol.

Natural Access Program Development

Natural Access is an NMS programming environment that allows developers without detailed SS7 knowledge to write application interfaces to SS7 APIs. Natural Access essentially provides a software shell around SS7 code, making the code transparent to the host-level operating system. In this way, Natural Access promotes faster development time and easier interfacing for the user.

TX Series Platform

NMS SS7 Version 3.x supports the TX3220 (PCI) and TX3220C (CompactPCI) platforms.


Technical Specifications:

Supported SS7 Protocols

  • MTP Layers 1 to 3 with redundancy
  • ISUP with redundancy
  • TUP with redundancy
  • SCCP with redundancy
  • TCAP with redundancy

Supported Host Operating Systems

  • Solaris 8 (32-bit mode) for Intel® x86 and SPARC® chips
  • Windows NT and Windows 2000

Programming Modules

  • Data APIs for ISUP, TUP, SCCP, TCAP, and MTP Layer 3
  • Management APIs for ISUP, TUP, SCCP, TCAP, and MTP Layers 2 and 3
  • Natural Access-based Health Management API for platform redundancy management


The NMS SS7 protocol stack implements the following functions and is compliant with the listed recommendations. In addition, users can take advantage of NMS Communications' Global Messaging Toolkit, which allows users to create support for any ETSI, ITU, or ANSI-based ISUP variant.


  • ETS 300-008-1, 300-308-2, ETSI, 1997
  • GF001-9001 (SS7 for National Telephone Network of China)
  • Q.701-702, ITU-T, 1992
  • Q.703-704, ITU-T, 1996
  • Q.707, ITU-T, 1992
  • Q.781-782, ITU-T, 1996
  • T1.111, 234, ANSI, 1992


  • China ISUP
  • EN 300-356-1, ETSI ISUP V.3, 1998
  • ETS 300-121, ETSI ISUP V.1, 1992
  • ETS 300-356-1, ETSI ISUP V.2, 1995
  • ETS 300-356-33, ETSI
  • Q.730-737, ITU-T, 1992
  • Q.761-764, ITU-T, 1997
  • Q.767, ITU-T, 1992
  • Q.784, ITU-T, 1996-1997
  • T1.113, 236, ANSI, 1995


  • Q.721–725, ITU-T, 1992
  • Q.783, ITU-T, 1992
  • GF001-9001


  • Q.711-715, ITU-T, 1996
  • Q.786, ITU-T
  • T1.112, 235, ANSI, 1995


  • Q.771-775, 787, ITU-T, 1997
  • T1.114, ANSI, 1992

Worldwide Deployment

NMS customers have successfully deployed SS7 equipment in major networks such as AT&T, British Telecom, Chung Hwa Telecom, Deutsche Telekom, France Telecom, NTT, Orange, Telefonica, Telstra, and others. NMS has enabled its customers to deploy SS7 in the following countries:

  • Argentina
  • Australia
  • Austria
  • Brazil
  • Belgium
  • Cambodia
  • Canada
  • China
  • Colombia
  • Croatia
  • Czech Republic
  • Finland
  • France
  • Germany
  • Haiti
  • Hungary
  • Iceland
  • Indonesia
  • Ireland
  • Israel
  • Italy
  • Japan
  • Korea
  • Lithuania
  • Malaysia
  • Mexico
  • Monaco
  • The Netherlands
  • New Zealand
  • Norway
  • Philippines
  • Russia
  • Singapore
  • South Africa
  • Spain
  • Sri Lanka
  • Surinam
  • Sweden
  • Switzerland
  • Taiwan
  • Thailand
  • United Kingdom
  • United States