When single registration indication flag will be set in ULR flags ?

Answer 1

If the Update Location request is to be sent due to an inter node (SGSN to MME) update and the previous SGSN does not support Idle Mode Signalling Reduction, the MME shall set the "Single-Registration-Indication" flag in the ULRFlags information element in the request.

Answer 2

From ts_129272v080101p document as it has been mentioned,

If the Update Location request is to be sent due to an inter node (SGSN to MME) update and the previous SGSN does not support Idle Mode Signalling Reduction, the MME shall set the "Single-Registration-Indication" flag in the ULRFlags information element in the request.