Section: 5.6.3 Notification procedure 5.6.3.1 General
Content: The notification procedure is used by the network: a) to request the UE, by sending the NOTIFICATION message over 3GPP access, to re-establish the user-plane resources of PDU session(s) associated with non-3GPP access over 3GPP access or to deliver 5GSM downlink signalling messages associated with non-3GPP access over 3GPP access when the UE is in 5GMM-IDLE mode over non-3GPP access and in 5GMM-CONNECTED mode over 3GPP access; or b) to request the UE, by sending the NOTIFICATION message over non-3GPP access, to re-establish user-plane resources of the PDU session(s) or to deliver downlink signalling associated with 3GPP access over 3GPP access when the UE is in 5GMM-CONNECTED mode over non-3GPP access and: 1) in 5GMM-IDLE mode over 3GPP access when the UE is not in MICO mode; or 2) in 5GMM-IDLE mode with suspend indication over 3GPP access when the UE is not in MICO mode. The network shall not use the NOTIFICATION message to re-establish user-plane resources of PDU session(s) associated with non-3GPP access over 3GPP access if all the PDU sessions of the UE that are established over the 3GPP access are associated with control plane only indication. . The network shall not use the NOTIFICATION message over non-3GPP access, if: a) the MUSIM UE supports the paging indication for voice services; b) the network has indicated "paging indication for voice services supported" to the UE; and c) the AMF detects that the downlink data is related to voice service (see 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [8]).