CSFB (Circuit Switched Fallback)

E123446

mobile network feature voice service continuity mechanism

CSFB (Circuit Switched Fallback) is a mobile network feature that allows LTE devices to temporarily switch to a legacy 2G/3G circuit-switched network to handle voice calls and SMS.

Try in SPARQL Jump to: Surface forms Disambiguation Statements Elicitation Referenced by

All labels observed (2)

Label	Occurrences
Circuit Switched Fallback	2
CSFB (Circuit Switched Fallback) canonical	1

How this entity was disambiguated

This entity first appeared as the object of triple T1077346 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: CSFB (Circuit Switched Fallback)
Context triple: [LTE, supports, CSFB (Circuit Switched Fallback)]

A. LTE
LTE (Long Term Evolution) is a high-speed wireless communication standard for mobile devices and data terminals, widely used as the foundation of 4G cellular networks.
B. UMTS
UMTS is a third-generation (3G) mobile telecommunications system that provides higher-speed voice and data services over cellular networks.
C. Mobile Networks
Mobile Networks is a Nokia business segment focused on providing mobile telecommunications infrastructure, technologies, and services for wireless network operators.
D. 5G Core
5G Core is the cloud-native, service-based core network architecture that underpins 5G mobile systems, enabling advanced connectivity, slicing, and low-latency services.
E. SMF
SMF is the three-letter IATA airport code for Sacramento International Airport, the primary commercial airport serving California’s capital city.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: CSFB (Circuit Switched Fallback)
Target entity description: CSFB (Circuit Switched Fallback) is a mobile network feature that allows LTE devices to temporarily switch to a legacy 2G/3G circuit-switched network to handle voice calls and SMS.

A. LTE
LTE (Long Term Evolution) is a high-speed wireless communication standard for mobile devices and data terminals, widely used as the foundation of 4G cellular networks.
B. UMTS
UMTS is a third-generation (3G) mobile telecommunications system that provides higher-speed voice and data services over cellular networks.
C. Mobile Networks
Mobile Networks is a Nokia business segment focused on providing mobile telecommunications infrastructure, technologies, and services for wireless network operators.
D. 5G Core
5G Core is the cloud-native, service-based core network architecture that underpins 5G mobile systems, enabling advanced connectivity, slicing, and low-latency services.
E. SMF
SMF is the three-letter IATA airport code for Sacramento International Airport, the primary commercial airport serving California’s capital city.
F. None of above. chosen

Statements (47)

Predicate	Object
instanceOf	mobile network feature ⓘ voice service continuity mechanism ⓘ
abbreviationOf	CSFB (Circuit Switched Fallback) self-linksurface differs ⓘ surface form: Circuit Switched Fallback
alternativeTo	SRVCC ⓘ VoLTE ⓘ
category	inter-RAT mobility feature ⓘ voice call continuity solution ⓘ
definedBy	3GPP ⓘ
enables	circuit-switched voice over legacy networks for LTE devices ⓘ
fullName	CSFB (Circuit Switched Fallback) self-linksurface differs ⓘ surface form: Circuit Switched Fallback
handoverType	fallback from LTE to 2G/3G for CS services ⓘ
impact	increases call setup delay compared to native VoLTE ⓘ requires radio reselection or handover from LTE to 2G/3G ⓘ
introducedFor	early LTE deployments without IMS voice ⓘ
lifecycleStage	legacy solution in many modern networks ⓘ
operatesWith	2G networks ⓘ 3G networks ⓘ GSM circuit-switched core network ⓘ UMTS ⓘ surface form: UMTS circuit-switched core network
predecessorOf	VoLTE-based voice services in LTE ⓘ
purpose	to provide voice and SMS service when LTE is packet-switched only ⓘ
relatedStandard	3GPP TS 23.272 ⓘ 3GPP TS 24-series ⓘ surface form: 3GPP TS 24.008 3GPP TS 29-series ⓘ surface form: 3GPP TS 29.118
replacedBy	VoLTE with IMS ⓘ VoNR in 5G standalone networks ⓘ
requires	dual-mode LTE and 2G/3G capable device ⓘ interworking between LTE and legacy CS core network ⓘ
requiresConfiguration	CSFB-capable tracking areas ⓘ SGs association between MME and MSC ⓘ
serviceType	circuit-switched voice support for LTE devices ⓘ
specifiedIn	3GPP Release 8 ⓘ
supports	mobile-originated SMS via CS domain ⓘ mobile-terminated SMS via CS domain ⓘ
supportsService	SMS ⓘ voice calls ⓘ
triggeredBy	SMS over SGs procedures ⓘ mobile-originated voice call ⓘ mobile-terminated voice call ⓘ
usedIn	E-UTRAN ⓘ LTE networks ⓘ
usedWhen	LTE network does not support native VoLTE ⓘ operator wants to reuse existing 2G/3G CS infrastructure for voice ⓘ
usesInterface	SGs interface ⓘ
usesNetworkElement	Mobility Management Entity ⓘ surface form: MME MSC ⓘ eNodeB ⓘ

How these facts were elicited

Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

LTE → supports → CSFB (Circuit Switched Fallback) ⓘ

CSFB (Circuit Switched Fallback) → fullName → CSFB (Circuit Switched Fallback) self-linksurface differs ⓘ

this entity surface form: Circuit Switched Fallback

CSFB (Circuit Switched Fallback) → abbreviationOf → CSFB (Circuit Switched Fallback) self-linksurface differs ⓘ