Section: 20.3.2 Home network domain name
Content: The home network domain name shall be in the form of an Internet domain name, e.g. operator.com, as specified in IETF RFC 1035 [19] and IETF RFC 1123 [20]. The home network domain name consists of one or more labels. Each label shall consist of the alphabetic characters (A-Z and a-z), digits (0-9) and the hyphen (-) in accordance with IETF RFC 1035 [19]. Each label shall begin and end with either an alphabetic character or a digit in accordance with IETF RFC 1123 [20]. The case of alphabetic characters is not significant. The MSC Server enhanced for ICS shall derive the home network domain name from the subscriber's IMSI as described in the following steps: 1. Take the first 5 or 6 digits, depending on whether a 2 or 3 digit MNC is used (see 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [27]) and separate them into MCC and MNC; if the MNC is 2 digits then a zero shall be added at the beginning. 2. Use the MCC and MNC derived in step 1 to create the "mnc<MNC>.mcc<MCC>.3gppnetwork.org" domain name. 3. Add the label "ics." to the beginning of the domain. An example of a home network domain name is: IMSI in use: 234150999999999; where: - MCC = 234; - MNC = 15; and - MSIN = 0999999999, which gives the home network domain name: ics.mnc015.mcc234.3gppnetwork.org