SIST EN 301 655 V1.2.1:2005

SIST EN 301 655 V1.2.1:2005 is the Slovenian adoption of ETSI EN 301 655 V1.2.1, which endorses ISO/IEC 15991:2003 with ETSI modifications. It specifies the Call Priority Interruption (CPI) and Call Priority Interruption Protection (CPIP) supplementary services for Private Integrated Services Network (PISN), so it is aimed at people who design, implement, or assess PISN services and signalling.

What does SIST EN 301 655 V1.2.1:2005 specify?

SIST EN 301 655 V1.2.1:2005 specifies the CPI and CPIP supplementary services for PISN and presents them as part of a family of standards for PISN services and signalling protocols. The document is an endorsement of ISO/IEC 15991 (2003), modified, so its main job is to adopt that international work into the ETSI framework.

The foreword places the standard in a series that uses ISDN concepts and conforms to the OSI framework. In practical terms, that tells readers that the service is defined in a telecom signalling context, not as a general-purpose application protocol.

The document’s structure is mainly:

• foreword and publication information
• an endorsement notice
• clause 3 modifications to references
• a reference-replacement table used throughout the text
• document history

What are the key requirements of SIST EN 301 655 V1.2.1:2005?

SIST EN 301 655 V1.2.1:2005 mainly tells readers how to read the base ISO/IEC text in ETSI terms. The important points are the reference rules, the added normative references, and the replacement of ISO/IEC citations with ETSI documents.

Reference handling in clause 3

The modified clause 3 explains how references in the document work:

• specific references stay tied to the cited edition
• non-specific references take the latest version
• if a referenced document is not easy to find, ETSI provides a reference location

This matters because implementers need to know whether they must follow a fixed edition or the current version of a companion standard.

ETSI references inserted into clause 3

The endorsement adds several normative references at the end of clause 3. These bring in the companion ETSI standards that the CPI and CPIP text relies on for bearer services, reference configurations, and related supplementary services.

Replacement of ISO/IEC references throughout the text

The document replaces several ISO/IEC references with ETSI equivalents throughout the base text. That means a reader should use the ETSI documents named here when following the PISN service description, not the original ISO/IEC citations in the endorsed text.

Terminology in the endorsed text

The endorsement also replaces the phrase “this International Standard” with “the present document”. This keeps the wording aligned with ETSI publication style and avoids confusion when the text is applied as a European standard.

Practical scope of the service definition

The standard is part of the PISN service family and sits alongside other supplementary services such as call transfer, call diversion, call completion, call interception, and path replacement. In practice, that means CPI and CPIP are intended to work within a larger PISN signalling environment, not as standalone features.

What terms does SIST EN 301 655 V1.2.1:2005 define?

SIST EN 301 655 V1.2.1:2005 uses several technical terms that are central to the document.

• PISN - Private Integrated Services Network, the network type covered by the standard.
• CPI - Call Priority Interruption, the supplementary service named in the title for handling priority calls.
• CPIP - Call Priority Interruption Protection, the companion supplementary service named in the title for protecting calls from interruption.
• ISDN - Integrated Services Digital Network, the concept base the series says it uses.
• OSI - Open Systems Interconnection, the framework the series says it conforms to.
• PTN - Private Telecommunication Network, a related network family named in the normative references.
• PTNX - PTN eXchange, the reference configuration term used for PTN exchanges.

Who uses SIST EN 301 655 V1.2.1:2005?

SIST EN 301 655 V1.2.1:2005 is used by telecom engineers, service designers, network equipment suppliers, and standards specialists working with PISN signalling and supplementary services. It is also relevant for testers and technical buyers who need to check whether a PISN implementation follows the ETSI-endorsed version of ISO/IEC 15991.

Which standards are used with SIST EN 301 655 V1.2.1:2005?

The endorsement adds these companion standards in clause 3:

• ETSI EN 300 171 - circuit-mode 64 kbit/s bearer services
• ETSI ETS 300 475-1 - PTN reference configuration for PTN exchanges
• ETSI EN 300 258 - path replacement additional network feature
• ETSI EN 300 260 - call transfer supplementary service
• ETSI EN 300 365 - call completion supplementary services
• ETSI EN 300 256 - call diversion supplementary service
• ETSI EN 301 256 - call interception Additional Network Feature (ANF)

These references tell the reader which other ETSI documents provide the surrounding service definitions and network model pieces needed to interpret the CPI and CPIP text.

What does the SIST EN 301 655 V1.2.1:2005 document contain?

The document is mainly an endorsement package rather than a long technical specification of its own. It contains the ETSI foreword, the endorsement notice for ISO/IEC 15991 (2003), a clause 3 update for references, and a table that maps ISO/IEC references to ETSI references.

It also includes national transposition dates and a short publication history. For practical use, the most important content is the reference mapping, because it shows which ETSI standards replace the ISO/IEC documents named in the base text.