Section: 20.3.3 Private User Identity
Content: The Private User Identity shall take the form of an NAI, and shall have the form "username@realm" as specified in clause 2.1 of IETF RFC 4282 [53]. The MSC Server enhanced for ICS shall derive the Private User Identity from the subscriber's IMSI as follows: 1. Use the whole string of digits as the username part of the private user identity; and 2. convert the leading digits of the IMSI, i.e. MNC and MCC, into a domain name, as described in clause 20.3.2. The result will be a Private User Identity of the form "<IMSI>@ics.mnc<MNC>.mcc<MCC>.3gppnetwork.org". For example if the IMSI is 234150999999999 (MCC = 234, MNC = 15), the private user identity then takes the form 234150999999999@ics.mnc015.mcc234.3gppnetwork.org