PSAP stands for Public-Safety Wnswering Point or Public-Safety Access Point. In our daily talks, it usually mean 'IMS based emergency call', i.e 'Emergency Call going through IMS network, not through CS call'.

Apr 4, 2012 · The support for emergency calls is required across the network and UE. Below is how the procedure works. First thing to consider is any UE can make an emergency call, provided network supports it.

The call flow is applicable following establishment of an emergency services session for eCall as described in clause 7.1.1 in which the initial MSD is transferred in the INVITE and prior to release of the emergency services session.

Here we explore an IMS to PSTN terminating call. The call flow covers the IMS-ISUP interworking and Megaco/H.248 interactions between the MGCF and IM-MGW. Call routing via the BGCF is also illustrated. An IMS call is analyzed with a focus on the SDP interactions involved in codec selection and QoS.

This document defines the stage 2 service description for emergency services in the IP Multimedia Core Network Subsystem (IMS), including the elements necessary to support IP Multimedia (IM) emergency services and IM emergency services for eCall.

VoLTE call flow and procedures is very big area to cover because of the many scenarios to consider from both UE and network perspective. In this article I will try to put some examples of VoLTE call flow from UE point of view. These procedures are the most important for VOLTE calls.

Jul 29, 2016 · Advances made to LTE/IMS networks, such as devices now must meet 3GPP standardized positioning performance tests, have created a new call flow when routing emergency calls.

In testing using a live network 40 out of 70 test cases failed to reliably reach the PSAP when 911 was called. Results of these tests show the need for updated regulations to ensure proper 911 …

Feb 20, 2023 · IMS – Voice over LTE (VoLTE): Emergency call is managed by the IMS Core Network. A CS and IMS capable UE attempting an emergency call follows TS 23.167. With 5G Core (5GC), the only way to manage the voice service is Voice over IMS (VoIMS). CS Fall-back is not supported with 5GC.

Detailed description of the procedure: Step 1. An IMS emergency call is initiated. Step 2. The E-CSCF sends an Invite message with 911 or other well-known emergency number as the dialled number, the UE's location information in a Location Object (LO) if available and the UE's media capabilities encapsulated in a SDP payload, to the ECS. Step 3.