Contents
1 Introduction
This document describes how to configure the MTAS Emergency State service in the Multimedia Telephony (MMTel) Application Server (AS). The service relies on the Emergency Call event notifications provided by the Serving Call Session Control Function (S-CSCF).
1.1 Prerequisites
It is assumed that the user of this document is familiar with the Operation and Maintenance (O&M) area, in general.
1.1.1 Licenses
Not applicable.
1.1.2 Documents
Before starting any of these procedures, the following documents must be available:
1.1.3 Conditions
Before starting any of these procedures, ensure that the following conditions are fulfilled:
- An Ericsson Command-Line Interface (ECLI) session in Exec mode is in progress.
- The IMS network is configured to deliver Emergency Call event notifications to MMTel AS.
2 Overview
The Emergency State service allows the application server to handle and keep track of emergency calls originated by the IMS users. The service maintains the Emergency Callback Window state of the IMS users, which can be used to control behavior of other MTAS services.
Since emergency calls are not routed through the application server, this service relies on the Emergency Call event notifications from the S-CSCF and maintains an Emergency Callback Window state for each served user. The service is also responsible for notifying the Online Charging System (OCS) when an emergency call starts for IMS subscribers.
The service is active when its administrative state is unlocked.
2.1 Subfunctions
The subfunctions included in the Emergency State service are described in this section.
2.1.1 Emergency Call Notifications
At the start of an emergency call of an IMS user, MTAS receives a SIP NOTIFY message with event "emergencyCall;start" from the S-CSCF. At the end of an emergency call, MTAS can receive another SIP NOTIFY message with event "emergencyCall;stop" from the S-CSCF.
As a response, MTAS sends a respective online charging event with "Emergency Call Start" or "Emergency Call End" indication to the OCS. It also sets the internal state of the Emergency Callback Window for the served user to "active", and starts an Emergency Callback Window timer. The time-out value of the timer depends on the event that triggered the start of the timer, and is determined by the configuration parameters, see Section 3.2.
The Emergency Callback Window state of the IMS user is active until the time-out of the Emergency Callback Window timer.
2.1.2 Emergency Callback Window Expiry
At the expiry of the Emergency Callback Window, the internal state of Emergency Callback Window for the user is set to "not active".
2.2 Interaction with Other Services
The service has no explicit interactions with other services, but the Emergency Callback Window state, which this service maintains for the IMS users that are served by the MMTel AS, can be accessed and used by other services. For example, invocation of STOD Call Pull can be disabled by the operator during an Emergency Callback Window.
3 Emergency State Service Configuration
The Emergency State service is configured through the Operations, Administration, and Maintenance (OAM) interface and controlled by the mtasEs Managed Object (MO). An overview of the MO structure is shown in Figure 1.
For configurable MOs and attributes related to the Emergency State service, refer to Managed Object Model (MOM).
3.1 Emergency State Administrative State Configuration
The Emergency State service is enabled by setting the mtasEsAdminState attribute in the mtasEs MO to 1 (Unlocked). If the mtasEsAdminState is set to 0 (Locked), the emergency state of the IMS user is not handled in MMTel AS.
3.2 Configure Emergency Callback Window Time-Outs
During ongoing emergency call, or directly after its completion, the Emergency Callback Window state of the IMS user is set to be active. Transition from this state is controlled by timers.
To configure the timers:
- Set the desired value in the CM attributes of the mtasEs MO in seconds, as follows:
- The mtasEsCbwStartTimer attribute sets the time-out for the Emergency Callback Window state after "emergencyCall;start" event notification has been received.
- The mtasEsCbwStopTimer attribute sets the time-out for Emergency Callback Window state after "emergencyCall;stop" event notification has been received.
4 Performance Management
Not applicable.
5 Fault Management
Not applicable.