This document describes how to implement the change(s) specified for Circuit Switch Fall Back (CSFB) activation in order to allow the voice and Short Messaging Service (SMS) with Mobile Switching Center (MSC)/Visitor Location Registry (VLR) over a subscriber group (SG) interface. The SG interface is between Mobility Management Entity (MME) in the Evolved Packet System (EPS) and the VLR, in order to allow location management coordination and in order to relay certain messages related to circuit switched services over the EPS system.
This is implemented on a MME deployed on Cisco Aggregated Service Router (ASR) 5x00 series (ASR5x00).
Ensure that you have Show Support Details (SSDs), bulkstat files, syslog files and any additional CLI output as required for the identified ASR5x00 nodes.
This document is not restricted to specific software and hardware versions.
The information in this document was created from the devices in a specific lab environment. All of the 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.
What is CSFB?
CSFB allows 3G/4G capable User Equipment (UE) to fallback to the 3G network for circuit switch functions, supports SMS, and voice calls.