Call-back to a UE that has made an emergency call via a visited IMS network

摘要: The 3GPP Technical Specifications stipulate that when an emergency call is made to centre such as a Public Safety Access Point (PSAP), special procedures are applied ensure the correctly routed and not interrupted. However, there may be situations where PSAP might want call-back UE after has been terminated (intentionally or unintentionally terminated). As specified in standards, established over IMS anchored entities serve through access network at which was attached (i.e. visited network, user's Home Network would case for normal call). current particular device require back right by indicating equipment identifier instance ID Globally Routable User Agent Uniform Resource Identifier (GRUU) provided during establishment (see TS 24.229). this requires IP-PSAP with enhanced functionality, something unlikely deployed many countries. This problem solved S-CSCF informed takes place without having route initial home network. P- CSCF (23) (21) informs (26) (22) user (e.g., contact address, GRUU). uses information terminating device.