SIST EN 301 921 V1.1.1:2005

SIST EN 301 921 V1.1.1:2005 is the Slovenian adoption of ETSI EN 301 921 V1.1.1, published by SIST for the European telecommunications standards series. It specifies the inter-exchange signalling protocol that supports the Simple Dialog supplementary service in a Private Integrated Services Network (PISN). It is written for people who design, integrate, or test PISN and QSIG-based services.

What does SIST EN 301 921 V1.1.1:2005 specify?

SIST EN 301 921 V1.1.1:2005 specifies how Simple Dialog works over the signalling interface used between PISN exchanges. In practice, it defines how keypad and display information is carried transparently so a user can communicate with another user or an application.

The document is organised as a European Standard that endorses ISO/IEC 21408 (2003) with ETSI modifications. Its front matter includes a foreword, an endorsement notice, clause 3 on normative references, and a history note.

What are the key requirements of SIST EN 301 921 V1.1.1:2005?

The main technical point is the signalling protocol at the Q reference point for the Simple Dialog supplementary service. That matters because implementers need to place the service at the correct network interface and make it work with other PISN signalling functions.

Protocol scope and placement

SIST EN 301 921 V1.1.1:2005 states that the protocol belongs to the PSS1 protocol, informally known as QSIG. For a designer or buyer, that means Simple Dialog is not a stand-alone feature - it sits inside the wider PISN signalling family.

What clause 3 changes

Clause 3 replaces the general reference text from ISO/IEC 21408 and adds ETSI normative references. It also replaces specific ISO/IEC references throughout the text with ETSI equivalents. In practice, users should follow the ETSI documents named in this standard when implementing or checking conformance.

The referenced building blocks

The added normative references point to the companion parts needed around the service:

• EN 300 172 for circuit-mode basic services
• ETS 300 475-1 for PTN reference configuration
• EN 300 239 for the generic functional protocol that supports supplementary services
• EN 301 920 for the Simple Dialog functional model and information flows

This tells engineers which other standards define the underlying service model and signalling environment.

Textual modifications

The standard also replaces the phrase "this International Standard" with "the present document". That keeps the ETSI version aligned with European standard wording and avoids ambiguity when the text is applied in practice.

What terms does SIST EN 301 921 V1.1.1:2005 define?

• PISN - Private Integrated Services Network, the private network environment in which the protocol operates.
• Simple Dialog - a supplementary service that lets a user exchange keypad and display information with another user or application.
• Q reference point - the network interface where the inter-exchange signalling protocol is applied.
• PSS1 - the protocol family that includes this signalling protocol, informally known as QSIG.
• QSIG - the informal name for the PSS1 signalling environment used in PISN systems.
• Supplementary service - a service added on top of basic telephony functions.
• ISDN - Integrated Services Digital Network, the concept base used by the series.
• OSI - Open Systems Interconnection, the framework that the series conforms to.

Who uses SIST EN 301 921 V1.1.1:2005?

SIST EN 301 921 V1.1.1:2005 is used by telecom equipment vendors, PBX and PISN system designers, signalling protocol implementers, and interoperability test teams. It is also relevant to quality managers and buyers who need to specify or verify support for Simple Dialog in private network equipment.

What changed in SIST EN 301 921 V1.1.1:2005 from the previous edition?

SIST EN 301 921 V1.1.1:2005 endorses ISO/IEC 21408 (2003) and applies ETSI modifications. The stated changes are the replacement of the generic reference wording in clause 3, the addition of four ETSI normative references, the substitution of several ISO/IEC references with ETSI documents, and the replacement of "this International Standard" with "the present document".

Which standards are used with SIST EN 301 921 V1.1.1:2005?

What does the SIST EN 301 921 V1.1.1:2005 document contain?

The document contains the endorsement material for ISO/IEC 21408 (2003), the clause 3 reference substitutions, and the publication history. It also identifies the service context - PISN, the Q reference point, and the PSS1/QSIG signalling family - so users can place Simple Dialog in the correct network architecture.

The technical content is centred on protocol specification and reference alignment rather than examples or implementation guidance. For users, the practical value is knowing which companion standards to consult when designing, integrating, or validating Simple Dialog support.