Section: 14.7.2 Format of W-APN Operator Identifier
Content: The W-APN Operator Identifier is composed of six labels. The last three labels shall be "pub.3gppnetwork.org". The second and third labels together shall uniquely identify the PLMN. The first label distinguishes the domain name as a W-APN. For each operator, there is a default W-APN Operator Identifier (i.e. domain name). This default W-APN Operator Identifier is derived from the IMSI as follows: "w-apn.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org" where: "mnc" and "mcc" serve as invariable identifiers for the following digits. <MNC> and <MCC> are derived from the components of the IMSI defined in clause 2.2. Alternatively, the default W-APN Operator Identifier is derived using the MNC and MCC of the VPLMN. See 3GPP TS 24.234[ 3GPP system to Wireless Local Area Network (WLAN) interworking; WLAN User Equipment (WLAN UE) to network protocols; Stage 3 ]  [48] for more information. The default W-APN Operator Identifier is used in both non-roaming and roaming situations when attempting to translate a W-APN consisting only of a Network Identifier into the IP address of the PDG in the HPLMN. In order to guarantee inter-PLMN DNS translation, the <MNC> and <MCC> coding used in the "w-apn.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org" format of the W-APN OI shall be: - <MNC> = 3 digits - <MCC> = 3 digits If there are only 2 significant digits in the MNC, one "0" digit shall be inserted at the left side to fill the 3 digits coding of MNC in the W-APN OI. As an example, the W-APN OI for MCC 345 and MNC 12 is coded in the DNS as: "w-apn.mnc012.mcc345.pub.3gppnetwork.org".