Cisco Cisco ASR 5000

Idle Mode Signalling Reduction on the S4-SGSN

▀ How ISR Works

▄ SGSN Administration Guide, StarOS Release 18

Figure 43. ISR Activation on the S4-SGSN

2G ISR Activation by the MME

The following illustration shows the ISR activation procedure when initiated by the MME for a 2G subscriber.

Note the following major procedural functions:



Context request from MME.



The SGSN sends a Context Response to the MME with the 'ISRSI' bit set provided all of following conditions

are satisfied:



The UE is EPC-capable.



The UE is ISR-capable.