SIST EN 300 257 V1.3.1:2005 PDF

Overview

SIST EN 300 257 V1.3.1:2005 specifies the inter-exchange signalling protocol for supporting call diversion supplementary services in Private Integrated Services Networks (PISN). Developed by SIST and based on the European Norm (EN 300 257 V1.3.1), this standard aligns with and modifies ISO/IEC 13873 (2003). Primarily targeting enterprise telecommunications, it defines how calls are redirected or forwarded between exchanges on a PISN, ensuring efficient, reliable, and interoperable communications.

This version incorporates essential updates, including:

• Corrections of errata from previous editions
• Migration to ASN.1 notation
• Introduction of a new procedure for delayed sending in DiversionLeg1

The standard forms a part of the QSIG family, widely adopted in business communications, and is essential for seamless call management and advanced telephony features across multi-site or complex network environments.

Key Topics

• Call Diversion Supplementary Services:

  • Call Forwarding Unconditional (SS-CFU)
  • Call Forwarding Busy (SS-CFB)
  • Call Forwarding No Reply (SS-CFNR)
  • Call Deflection (SS-CD)

• Inter-exchange Signalling: Defines signalling at the Q reference point between PISN exchanges, supporting advanced call handling across private networks.

• QSIG Protocol: This standard builds on QSIG, the widely used PISN signalling protocol for interoperability and supplementary service support.

• ASN.1 Migration: Updates protocol notation to ASN.1 for improved clarity and compatibility with modern telecommunications systems.

• Error Corrections and New Procedures: Implements corrections and newly specified delayed sending procedures, enhancing overall protocol reliability.

Applications

The standard is crucial for organizations that operate interconnected private telephone exchanges, commonly found in:

• Enterprise Telephony: Multisite businesses requiring internal call transparency, call forwarding, and efficient intra-organizational communication.
• Unified Communications Systems: Vendors implementing advanced call management features in PBX systems and IP telephony platforms.
• Interoperability Solutions: Facilitates seamless communication between varied vendor equipment supporting the QSIG protocol stack.
• Network Modernization: Enables migration from legacy to modern signalling notations (ASN.1), ensuring long-term compatibility.

Typical scenarios include:

• Automatic call forwarding for unavailable or busy users
• Transparent call deflection to alternate destinations
• Enhanced user experience for both callers and operators
• Reduced missed communications and improved organizational responsiveness

Related Standards

For comprehensive implementation and integration, the following standards are closely associated with SIST EN 300 257 V1.3.1:

• EN 300 172: Circuit-mode basic services
• EN 300 171: 64 kbit/s bearer services functional capabilities
• ETSI ETS 300 475-1: Reference configurations for PTN exchanges
• EN 300 239: Generic functional protocol for supplementary services
• EN 300 238: Name identification supplementary service
• EN 300 261: Call transfer supplementary service
• EN 300 366: Call completion supplementary services
• EN 300 256: Call diversion supplementary service specification and flows

These standards collectively support robust and interoperable enterprise telephony systems, ensure open systems interconnection, and streamline advanced services deployment within PISN environments. Implementers are encouraged to consult the full set for optimal network performance and feature integration.

Keywords: private integrated services network, PISN, call diversion, inter-exchange signalling protocol, QSIG, telecommunications standards, supplementary services, enterprise telephony, ASN.1, call forwarding, SIST EN 300 257.