SIST EN 301 255 V1.2.1:2005

SIST EN 301 255 V1.2.1:2005 is the Slovenian adoption of ETSI EN 301 255 V1.2.1, a European standard for Private Integrated Services Network (PISN) signalling. It specifies the inter-exchange signalling protocol for the Message waiting indication supplementary service at the Q reference point, for use in PSS1, also known as QSIG.

What does SIST EN 301 255 V1.2.1:2005 specify?

SIST EN 301 255 V1.2.1:2005 specifies the signalling protocol used between exchanges in a PISN to support Message waiting indication (MWI). The foreword places it in the family of PISN service and signalling standards and says it forms part of the PSS1 protocol.

The document is an endorsement of ISO/IEC 15506 (2003) with ETSI modifications. In practice, that means implementers use the ISO/IEC base while following the ETSI reference substitutions and wording changes listed in the endorsement notice.

The visible structure in the document includes the foreword, the endorsement notice, clause 3 on normative references, and a history section. Clause 3 is the main place where the international standard is adapted for this European publication.

What are the key requirements of SIST EN 301 255 V1.2.1:2005?

SIST EN 301 255 V1.2.1:2005 is mainly a conformance and reference document for the MWI signalling protocol. Its key technical content is the set of reference substitutions and the rules for using referenced documents.

Protocol scope and context

The standard specifies signalling at the Q reference point for the MWI supplementary service. For network designers, that means the protocol must fit the PISN inter-exchange signalling environment rather than a generic telephone network interface.

Reference handling rules

Clause 3 states how references are to be interpreted:

• specific references stay fixed to the cited version
• non-specific references use the latest version

This matters when implementing or testing against the standard, because the version of a referenced document can change what applies.

ETSI normative references added in clause 3

Clause 3 adds these normative references at the end of the reference list:

• ETS 300 475-1 for PTN reference configuration for PTNXs
• EN 300 239 for the generic functional protocol supporting supplementary services
• EN 300 257 for Call diversion supplementary service
• EN 301 260 for MWI functional models and information flows

For readers, these references show which companion standards are needed to understand the surrounding signalling framework and related supplementary services.

Reference replacements throughout the text

The document replaces the ISO/IEC references in ISO/IEC 15506 with ETSI equivalents:

• ISO/IEC 11579-1 becomes ETS 300 475-1
• ISO/IEC 11582 becomes EN 300 239
• ISO/IEC 13873 becomes EN 300 257
• ISO/IEC 15505 becomes EN 301 260

This is important in practice because the ETSI version points implementers to the European standards that apply in this publication.

Terminology used by the publication

The text also replaces the phrase “this International Standard” with “the present document”. That wording tells readers that the ETSI publication is the operative reference text, not the original international wording.

What terms does SIST EN 301 255 V1.2.1:2005 define?

SIST EN 301 255 V1.2.1:2005 uses several core terms from the PISN signalling domain.

• Private Integrated Services Network (PISN) - the network environment covered by the standard.
• Message waiting indication (MWI) - the supplementary service that informs a user that a message is waiting.
• PSS1 - the PISN signalling system that the protocol belongs to.
• QSIG - the informal name used for the PSS1 protocol family.
• Q reference point - the signalling reference point where the protocol applies.
• Integrated Services Digital Network (ISDN) - the concept base used for the PISN standards family.
• Open Systems Interconnection (OSI) - the framework mentioned in the foreword for the standards structure.

Who uses SIST EN 301 255 V1.2.1:2005?

SIST EN 301 255 V1.2.1:2005 is used by telecommunications engineers, PBX and PISN equipment vendors, and interoperability test teams. It is also relevant to standards specialists and buyers who need MWI support in private network signalling.

In practice, these users rely on it to design, implement, or check inter-exchange signalling for message waiting indication, and to align their equipment with the ETSI/ISO/IEC framework used for PISN and QSIG.

What changed in SIST EN 301 255 V1.2.1:2005 from the previous edition?

The scope describes this edition as a second edition of ETS 300 255 that adds support for additional services, including multimedia. It is also presented as a third edition of ECMA-242 on message waiting indication.

Which standards are used with SIST EN 301 255 V1.2.1:2005?

SIST EN 301 255 V1.2.1:2005 works alongside the standards named in clause 3:

• ETS 300 475-1 - PTN reference configuration for PTNXs
• EN 300 239 - generic functional protocol for supplementary services
• EN 300 257 - Call diversion supplementary service
• EN 301 260 - MWI functional models and information flows

These documents supply the surrounding reference configuration, service framework, and related supplementary-service behavior.

What does the SIST EN 301 255 V1.2.1:2005 document contain?

SIST EN 301 255 V1.2.1:2005 contains a foreword describing its place in the PISN standards family, an endorsement notice, and the clause 3 reference updates that adapt ISO/IEC 15506 for ETSI use. It also includes a replacement table that maps international references to ETSI references.

The document shows the publication history and the transposition dates for European standard adoption and national withdrawal. For implementation work, the most useful parts are the protocol scope, the normative reference list, and the reference substitution table, because they determine which companion standards apply.