Question: What is the correct format for constructing the Short Message Service Function (SMSF) Fully Qualified Domain Name (FQDN)?
Option 1: <label(s) assigned by a PLMN>.smsf.5gc.mnc<MNC>.mcc<MCC>.3gppnetwork.org
Option 2: smsf.<label(s) assigned by a PLMN>.5gc.mnc<MNC>.mcc<MCC>.3gppnetwork.org
Option 3: smsf.<label(s) assigned by a PLMN>.5gc.mnc<MNC>.mcc<MCC>.3gppnetwork.org is incorrect, the correct format is <label(s) assigned by a PLMN> should be prefixed with "smsf" and then followed by Home Network Domain Name
Option 4: 5gc.mnc<MNC>.mcc<MCC>.3gppnetwork.org.smsf.<label(s) assigned by a PLMN>
Explanation: The correct format for constructing the Short Message Service Function (SMSF) Fully Qualified Domain Name (FQDN) is by prefixing its Home Network Domain Name with the label "smsf" and with label(s) assigned by a PLMN, as specified in the 3GPP TS 23.003 standard.