Section: 14.7.1 Format of W-APN Network Identifier
Content: The W-APN Network Identifier follows the format defined for APNs in clause 9.1.1. In addition to what has been defined in clause 9.1.1 the W-APN Network Identifier shall not contain "w-apn." and not end in ".3gppnetwork.org". A W-APN Network Identifier may be used to access a service associated with a PDG. This may be achieved by defining: - a W-APN which corresponds to a FQDN of a PDG, and which is locally interpreted by the PDG as a request for a specific service, or - a W-APN Network Identifier consisting of 3 or more labels and starting with a Reserved Service Label, or a W-APN Network Identifier consisting of a Reserved Service Label alone, which indicates a PDG by the nature of the requested service. Reserved Service Labels and the corresponding services they stand for shall be agreed between operators who have WLAN roaming agreements. The W-APN Network Identifier for the support of IMS Emergency calls shall take the form of a common, reserved Network Identifier of the form "sos". As an example, the W-APN for MCC 345 and MNC 12 is coded in the DNS as: "sos.w-apn.mnc012.mcc345.pub.3gppnetwork.org". where "sos" is the W-APN Network Identifier and " mnc012.mcc345.pub.3gppnetwork.org " is the W-APN Operator Identifier.