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.