- When the Network Initiated Deregistration Event occurs in S-CSCF1, S-CSCF1 informs the HSS that the user is no longer registered. S-CSCF1 either notifies the HSS to clear or requests to keep its location information for that subscriber. The HSS then either clears or keeps S-CSCF1 name for that subscriber according to request. In case S-CSCF1 location information is cleared from the HSS, the state of the subscriber identity is stored as "not registered" in the HSS. In case S-CSCF1 location information is kept in the HSS, the state of the subscriber identity is stored as "unregistered" in the HSS and S-CSCF1. The HSS acknowledges the request.