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Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)

superseded recommendation/international standard from the International Telecommunication Union
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Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)

Summary

Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI) is an ITU-T recommendation version[1].

Key Facts

  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s instance of is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — instance of (P31): ITU-T recommendation version[2].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s publisher is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — publisher (P123): ITU Telecommunication Standardization Sector[3].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s edition number is recorded as 11/1988[4].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s language of work or name is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — language of work or name (P407): English[5].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s publication date is recorded as +1988-11-25T00:00:00Z[6].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s official website is recorded as https://www.itu.int/rec/T-REC-I.251.1-198811-S/en[7].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s work available at URL is recorded as https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-I.251.1-198811-S!!PDF-E&type=items[8].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s number of pages is recorded as {'unit': '1', 'amount': '+8'}[9].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s standards body is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — standards body (P1462): International Telecommunication Union[10].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s title is recorded as Number identification supplementary services: Direct-Dialling-In (DDI)[11].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s cites work is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — cites work (P2860): Recommendation I.130 (11/1988): Method for the characterization of telecommunication services supported by an ISDN and network capabilities of an ISDN[12].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s cites work is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — cites work (P2860): Recommendation I.140 (11/1988): Attribute technique for the characterization of telecommunication services supported by an ISDN and network capabilities of an ISDN[13].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s cites work is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — cites work (P2860): Recommendation I.210 (11/1988): Principles of telecommunication services supported by an ISDN and the means to describe them[14].
  • Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s ITU-T Recommendation is recorded as I.251.1 (11/1988)[15].

Body

Authorship and Creation

Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s publisher is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — publisher (P123): ITU Telecommunication Standardization Sector[3].

Publication

Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)'s publication date is recorded as +1988-11-25T00:00:00Z[6]. Its language of work or name is recorded as Number identification supplementary services: Direct-Dialling-In (DDI) — language of work or name (P407): English[5].

References

Programmatic citations — every numbered marker resolves to a verifiable graph row below.

Direct Wikidata claims

  1. [2] ↑ . wikidata.org.
  2. [3] ↑ . wikidata.org.
  3. [4] ↑ . wikidata.org.
  4. [5] ↑ . wikidata.org.
  5. [6] ↑ . wikidata.org.
  6. [7] ↑ . wikidata.org.
  7. [8] ↑ . wikidata.org.
  8. [9] ↑ . wikidata.org.
  9. [10] ↑ . wikidata.org.
  10. [11] ↑ . wikidata.org.
  11. [12] ↑ . wikidata.org.
  12. [13] ↑ . wikidata.org.
  13. [14] ↑ . wikidata.org.
  14. [15] ↑ . wikidata.org.

Class ancestry

  1. [1] ↑ . Wikidata. wikidata.org.

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Use these citations when quoting this entity in research, articles, AI prompts, or wherever provenance matters. We aggregate Wikidata + Wikipedia + authoritative open-data sources; the stitched, scored, cross-referenced view is what 4ort.xyz contributes.

APA 4ort.xyz Knowledge Graph. (2026). Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI). Retrieved May 3, 2026, from https://4ort.xyz/entity/recommendation-i-251-1-11-1988-number-identification-supplementary-services-direct-dialling-in-ddi-
MLA “Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI).” 4ort.xyz Knowledge Graph, 4ort.xyz, 3 May. 2026, https://4ort.xyz/entity/recommendation-i-251-1-11-1988-number-identification-supplementary-services-direct-dialling-in-ddi-.
BibTeX @misc{4ortxyz_recommendation-i-251-1-11-1988-number-identification-supplementary-services-direct-dialling-in-ddi-_2026, author = {{4ort.xyz Knowledge Graph}}, title = {{Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI)}}, year = {2026}, url = {https://4ort.xyz/entity/recommendation-i-251-1-11-1988-number-identification-supplementary-services-direct-dialling-in-ddi-}, note = {Accessed: 2026-05-03}}
LLM prompt According to 4ort.xyz Knowledge Graph (aggregator of Wikidata, Wikipedia, and authoritative open-data sources): Recommendation I.251.1 (11/1988): Number identification supplementary services: Direct-Dialling-In (DDI) — https://4ort.xyz/entity/recommendation-i-251-1-11-1988-number-identification-supplementary-services-direct-dialling-in-ddi- (retrieved 2026-05-03)

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