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Specification

3GPP TS 23.172: Technical realization of Circuit Switched (CS) multimedia service UDI/RDI fallback and service modification; Stage 2

Published 2026-10-16Updated 2026-10-16

At a glance

Title
Technical realization of Circuit Switched (CS) multimedia service UDI/RDI fallback and service modification; Stage 2
Newest version
V19.0.0 (Rel-19)
Versions indexed
4
Newest per release
Rel-15: V15.0.0 (2018-07-03); Rel-16: V16.0.0 (2020-07-10); Rel-17: V17.0.0 (2022-03-29); Rel-19: V19.0.0 (2025-10-02)

In plain words

TS 23.172 describes Service Change and UDI Fallback (SCUDIF) for UDI/RDI multimedia calls, including "when signalling of the feature is not possible in the network (fallback to preferred service or speech)". It covers successful call establishment when end-to-end circuit-switched (CS) multimedia is not possible, and swapping between multimedia and basic speech during an established call.

Source: 3GPP TS 23.172 V19.0.0, clause 1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/23_series/23.172/23172-j00.zip

Sources

  1. 3GPP TS 23.172 V19.0.0, clause 1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/23_series/23.172/23172-j00.zip

How this page was made

The facts box comes straight from the 3GPP TDoc list and specification archive as indexed by 3GPP Scout. An AI model (GPT-6 Luna) wrote the paragraph and named the source of each sentence. Code checked every quote word for word against the stored source text and every number against the cited source. A second AI model from another company (Claude Opus 5.5) reviewed the paragraph against the same sources. The 3GPP documents themselves govern.