J.2 Retrieval of emergency call numbers

24.3023GPPAccess to the 3GPP Evolved Packet Core (EPC) via non-3GPP access networksRelease 18Stage 3TS

When a UE is connected to WLAN access, the UE may support the DNS mechanisms specified in this Annex to retrieve emergency call numbers and service types for use within the country indicated by the MCC information.

The UE shall construct an emergency number FQDN based on the Country based Emergency Numbers FQDN format as specified in 3GPP TS 23.003 [3] and then perform the DNS NAPTR query using the constructed emergency number FQDN as input.

If the result of this query is:

– a set of one or more records containing the replacement field of the form "<emergency-type>.<emergency-number>.sos.en.epc.mcc<MCC>.visited-country.pub.3gppnework.org", the UE shall consider the list of emergency-number(s) and type(s) as valid additional emergency call number(s) for the country indicated by the MCC information and store the emergency call number(s) and type(s) received;

NOTE: Even though a label named "visited-country" is present in the replacement field, the UE can use the mechanism to obtain emergency numbers and associated type(s) even when the UE is in its home country.

– no records containing the replacement field of the form "<emergency-number>.<emergency-type>.sos.en.epc.mcc<MCC>.visited-country.pub.3gppnework.org", the UE shall replace a Local Emergency Numbers List storing emergency call number(s) and type(s) received over WLAN with an empty Local Emergency Numbers List.