SIST EN 300 485 V1.2.3:2005

• Abstract:

  The specification of the usage of the cause and location fields in the DSS1 signalling protocol as an endoresement of ITU-T Recommendation Q.850 (1997).

• Status: Published
• Publication Date: 31-Mar-2005
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2005
• Due Date: 01-Apr-2005
• Completion Date: 01-Apr-2005
• Ref Project: ETSI EN 300 485 V1.2.3 (1999-10) - Integrated Services Digital Network (ISDN); Definition and usage of cause and location in Digital Subscriber Signalling System No. one (DSS1) and Signalling System No.7 ISDN User Part (ISUP) [ITU-T Recommendation Q.850 (1998), modified]

SIST EN 300 485 V1.2.3:2005 is the Slovenian adoption of ETSI EN 300 485 V1.2.3, a European standard for Integrated Services Digital Network (ISDN) signalling. It specifies how the cause and location fields are used in Digital Subscriber Signalling System No. one (DSS1) and Signalling System No.7 ISDN User Part (ISUP), for engineers and vendors implementing or testing ISDN call control.

What does SIST EN 300 485 V1.2.3:2005 specify?

SIST EN 300 485 V1.2.3:2005 specifies the use of the cause and location fields in DSS1 signalling, as an endorsement of ITU-T Recommendation Q.850 with ETSI modifications. In practice, it tells implementers how to code and interpret these fields so that ISDN equipment uses the same signalling conventions.

The document follows the structure of the endorsed ITU-T text and adds ETSI-specific material. Its main parts include a references clause inserted after subclause 1.1, modifications to the coding text in clause 2, a new clause 6 for ETSI DSS1 cause values, and the document history.

What are the key requirements of SIST EN 300 485 V1.2.3:2005?

SIST EN 300 485 V1.2.3:2005 applies the elements of ITU-T Recommendation Q.850 with modifications. The document marks new or changed text with sidebars, and uses underlining or strike-out where needed. For users, this means the ETSI version is the one to implement, not the unmodified ITU-T text.

DSS1 cause value coding

In the DSS1 cause values, the coding of octets 3 and 5 is the same as for standardized cause values. This keeps the field layout aligned with the established ITU-T format and helps equipment decode cause information consistently.

For ETSI DSS1 cause values, the coding standard in octet 3, bits 7 and 6, is coded as "10" for national standard. In practice, this distinguishes ETSI DSS1 cause values from other coding standards during signalling exchange.

ETSI DSS1 cause values

Clause 6 adds guidance for allocating national cause values in ETSI DSS1. It recommends using the same classification for national values as for the ITU-T coding standard, and it gives a coding principle that separates national standard and ETSI standard values. This matters when designing switch software or protocol stacks, because the bit pattern must match the intended cause value class.

Reference handling

The added references clause explains how references are treated in the document. Specific references are fixed to the edition named, while non-specific references follow the latest version, and non-specific ETS references are taken to include later EN versions with the same number. This is important when checking which companion standard to implement or test against.

What terms does SIST EN 300 485 V1.2.3:2005 define?

• DSS1 - Digital Subscriber Signalling System No. one, the ISDN signalling protocol used on the subscriber side.
• ISDN - Integrated Services Digital Network, the telecommunication environment addressed by the standard.
• ISUP - ISDN User Part of Signalling System No.7, the call-control signalling part used in the network.
• SS7 - Signalling System No.7, the signalling system that carries ISUP.
• cause values - Encoded reasons for call clearing or related signalling events.
• location - The field that identifies where the cause originated.
• coding standard - The code in octet 3, bits 7 and 6, that identifies the standard used for the cause value.

Who uses SIST EN 300 485 V1.2.3:2005?

SIST EN 300 485 V1.2.3:2005 is used by ISDN equipment manufacturers, signalling protocol developers, telecom network operators, and conformance test laboratories. It is also relevant to quality and procurement teams that need to check whether DSS1 or ISUP equipment uses the expected cause and location coding.

In practice, these users apply the standard when implementing call-control signalling, checking interoperability between networks and terminals, and verifying that national and ETSI cause values are encoded correctly.

What changed in SIST EN 300 485 V1.2.3:2005 from the previous edition?

SIST EN 300 485 V1.2.3:2005 is a modified endorsement of ITU-T Recommendation Q.850. The changes stated in the document are:

• a references clause is inserted after subclause 1.1
• references to ITU-T Recommendation Q.730, Q.763 and Q.931 are replaced with the corresponding modified ETSI EN references
• a sentence is added after figure 1/Q.850 so that ETSI DSS1 cause octets 3 and 5 follow the standardized coding
• clause 2.2.2 is extended so that the ETSI DSS1 coding standard uses "10" for national standard
• a new clause 6 is added for ETSI DSS1 cause values

The document also notes that modified text is shown with sidebars, and detailed changes may be highlighted with underlining or strike-out.

Which standards are used with SIST EN 300 485 V1.2.3:2005?

Reference	What it contributes
EN 300 356-1	ISUP version 3 for the international interface, including basic services, used for the modified reference to ITU-T Recommendation Q.763.
EN 300 356-2	ISUP version 3 for the international interface, including ISDN supplementary services, used for the modified reference to ITU-T Recommendation Q.730.
EN 300 403-1 (V1.2)	DSS1 protocol for circuit-mode basic call control, used for the modified reference to ITU-T Recommendation Q.931.

What does the SIST EN 300 485 V1.2.3:2005 document contain?

SIST EN 300 485 V1.2.3:2005 contains a references section, ETSI modifications to the Q.850 text, and a new clause on ETSI DSS1 cause values. It also includes the specific note that octets 3 and 5 follow the standardized coding for ETSI DSS1 cause values, and the coding-standard rule for octet 3.

The document uses one referenced figure, figure 1/Q.850, to anchor the format discussion, and a coding table in clause 6 to show how national standard and ETSI standard values are distinguished. These parts are the practical core of the document for implementation and interoperability work.

SLOVENSKI STANDARD
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Integrated Services Digital Network (ISDN); Definition and usage of cause and location in
Digital Subscriber Signalling System No. one (DSS1) and Signalling System No.7 ISDN
User Part (ISUP) [ITU-T Recommendation Q.850 (1998), modified]
Ta slovenski standard je istoveten z: EN 300 485 Version 1.2.3
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
Definition and usage of cause and location in
Digital Subscriber Signalling System No. one (DSS1) and
Signalling System No.7 ISDN User Part (ISUP)
[ITU-T Recommendation Q.850 (1998), modified]

2 ETSI EN 300 485 V1.2.3 (1999-10)
Reference
REN/SPS-01048 (4ho00iq0.PDF)
Keywords
DSS1, ISDN, ISUP, SS7
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ETSI
3 ETSI EN 300 485 V1.2.3 (1999-10)
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Foreword
This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Signalling
Protocols and Switching (SPS).
National transposition dates
Date of adoption of this EN: 22 October
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