Cisco Cisco ASR 5500 Leaflet

devices used in this document started with a cleared (default) configuration. If your network is live, make sure
that you understand the potential impact of any command.

CSFB allows 3G/4G capable User Equipment (UE) to fallback to the 3G network for circuit switch functions,
supports SMS, and voice calls.

3rd Generation Partnership Project (3GPP) Technical Specfications (TS) 23.272: Circuit Switch (CS)
fallback in EPS

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3GPP TS 29.118: SG interface specification

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This diagram is based upon SGs that use Steam Control Tranmission Protocol (SCTP) for transport: