Question: What is the correct format for deriving a Private User Identity from an IMSI (International Mobile Subscriber Identity) for a non-SNPN (Stand-alone Non-Public Network) subscriber in 3GPP systems?
Option 1: <IMSI>@mcc<MCC>.mnc<MNC>.gsm.org
Option 2: <IMSI>@ims.mnc<MNC>.mcc<MCC>.3gppnetwork.org
Option 3: username@realm.3gppnetwork.org (where username and realm are not directly derived from IMSI)
Option 4: <IMSI>@mnc<MNC>.mcc<MCC>.ims.3gppnetwork.org
Explanation: According to the specified derivation process for 3GPP systems, when creating a Private User Identity from an IMSI, the correct format involves using the entire IMSI string as the username and converting the leading digits (MCC and MNC) into a specific domain name format. This results in the Private User Identity taking the form <IMSI>@ims.mnc<MNC>.mcc<MCC>.3gppnetwork.org, which matches Option 2. This process ensures a standardized and unique identification method within the network.