MTAS Three Party Management Guide
MTAS

Contents

1Introduction
1.1Prerequisites

2
Overview
2.1Subfunctions
2.2Interaction with Other Services

3
3PTY Configuration
3.1Configuration Activities
3.23PTY Administrative State Configuration
3.3Wholesale for 3PTY Configuration
3.4Service Data Configuration

4
Performance Management

5
Fault Management

1   Introduction

This document describes how to configure the Three Party (3PTY) session service in the MTAS.

1.1   Prerequisites

It is assumed that the user of this document is familiar with the O&M area, in general.

1.1.1   Licenses

To enable basic services in the MTAS, the MMTel license must be installed.

For more information about the MMTel license, refer to MTAS Licenses.

1.1.2   Documents

Before starting any procedure in this document, ensure that the following documents are available:

1.1.3   Conditions

The following condition must apply:

An Ericsson Command-Line Interface (ECLI) session in Exec mode is in progress.

2   Overview

This document describes the basic 3PTY service that the MTAS offers to its subscribers.

The service allows a user who is involved in two separate Two Party (2PTY) sessions with two other participants to convert to a 3PTY session by reusing the existing dialogs from the 2PTY sessions. The user starting the 3PTY session is called "3PTY originator" and is able to toggle participants in and out of the 3PTY session. Both 2PTY sessions have to be put on hold before the request for the 3PTY session is issued. The 3PTY originator has a possibility to resume back to 2PTY session with any of the 3PTY participants.

For 3PTY-sequence, refer to the 3GPP 24.605 standard.

Although the 3PTY service is provisioned and activated for the served user, a 3PTY session establishment attempt can be suppressed using the Flexible Service Format Selection (FSFS) service. For details about the service interaction between the 3PTY and FSFS services, see Section 2.2.5 Flexible Service Format Selection.

2.1   Subfunctions

The 3PTY session service function consists of the following subfunctions:

2.1.1   3PTY Service

The 3PTY service is the central administrator of a 3PTY session. It applies policies, controls the MRFP, and maintains a signaling relationship with the participants involved in the 3PTY session, and interworks with other services when required.

A 3PTY session is started by sending an INVITE to a 3PTY Factory. Upon the receipt of the INVITE with URI-list, the 3PTY service verifies the following:

If any of these conditions are not fulfilled, the request is rejected, 403 Forbidden. In the case where 3PTY is suppressed by the FSFS service, the 403 Forbidden contains the warning header "The service is suppressed".

Following the successful validation of the request for a 3PTY session, the 3PTY service initiates creation of the 3PTY session by sending re-INVITE requests to the 3PTY participants on the same dialogs that have been used in the 2PTY sessions to the participants. The same media types used in the 2PTY sessions are also used in 3PTY sessions.

Note:  
3PTY must have an SDP in the 3PTY INVITE to work properly. If it does not get an SDP, it rejects the INVITE with 403 Forbidden.

2.1.2   3PTY Policy

The 3PTY policies are static, which means they do not change between 3PTY sessions, nor do they change during a session.

The policies enforced by the 3PTY service are as follows:

2.1.3   3PTY Media Handling

The 3PTY service supports audio and video media types in the 3PTY session. To ensure that the SDP offer answer specifications for SIP are met, the media types included in the re-INVITE on the existing 2PTY sessions with the 3PTY participants can only include media types which were included in the SDP of the original 2PTY session. While it is valid to include additional media types in the SDP offer included in the re-INVITE to the remote 3PTY participants, only the media capabilities that were negotiated on the original session is offered.

The SDP offer included in each of the re-INVITE requests to the remote parties include all the media types included in the SDP exchanged between the 3PTY originator and the remote party in the 2PTY session in the same order as it was included in the 2PTY session. Only media lines for which media streams were requested from the 3PTY MRFP has an active port number, that is, non-zero. All other media types have the port number set to zero, that is, these media types are not usable. Only one audio and one video stream are supported. The reason for this policy is that it would be difficult to revert to the previously negotiated SDP when resuming to a 2PTY session.

An example of a 3PTY media handling is given in Example 1.

Example 1   3PTY Media Handling

The 3PTY originator and a remote party are in a 2PTY session
in which only audio media was included in the SDP exchanged
in the session setup. No additional media has been requested
in the session. A second session is established between the
3PTY originator and a second remote party which uses audio,
video, and text media types. The 3PTY originator then
requests the establishment of a 3PTY session between himself
and the two remote parties that are on Hold.
The request is for an audio and video 3PTY session.

Media offered to the participants are as follows:

The media in the SDP in the re-INVITEs is as follows:

2.2   Interaction with Other Services

This section describes how the 3PTY interact with other services.

2.2.1   Hold

The 3PTY service uses the Hold service when playing announcements on dialogs that are put on hold.

For more information about the Hold service, refer to MTAS Hold Communication Management Guide.

2.2.2   Call Admission Control

The 3PTY originator has two dialogs when the request for a 3PTY call is received by the MTAS. The request for a 3PTY call is counted as one call, thus the user must have a Call Admission Control (CAC) limit of at least three to be able to make a 3PTY call.

For more information about the CAC service, refer to MTAS Call Admission Control Management Guide.

2.2.3   Advise of Charge

No Advice of Charge (AoC) information is sent to the user on the SIP dialog for requesting a 3PTY call. The AoC information is sent on the SIP dialogs for the 2PTY calls.

For more information about the AoC service, refer to MTAS Advice of Charge Management Guide.

2.2.4   Charging

The communication request initiating the 3PTY session is treated as an originating session for charging purposes. Charging for the original 2PTY sessions (A-B and A-C) continues throughout the period that the sessions are included in the 3PTY session.

The following service-specific AVPs are applicable to charging for the 3PTY session.

For further details of the charging actions performed by the MTAS, refer to the following documents:

2.2.5   Flexible Service Format Selection

The 3PTY service can be suppressed using the FSFS service. When at least one of the 2-party dialogs is indicated by the FSFS service to be suppressed from joining any 3PTY session, the user is not able to initiate the 3PTY service. The 3PTY service invocation attempt is responded with 403 Forbidden containing the warning header "The service is suppressed".

For more information about the FSFS service, refer to MTAS Flexible Service Format Selection Management Guide.

3   3PTY Configuration

The 3PTY service is controlled by the Mtas3pty Managed Object (MO). An overview of the Identity Presentation MO structure is shown in Figure 1.

Figure 1   3PTY MO Structure

Configurable MOs and attributes related to the 3PTY services are defined in Managed Object Model (MOM).

3.1   Configuration Activities

More configuration activities are listed in Table 1.

Table 1    Configuration Activities

Activity

Attribute

Defining the 3PTY factory URI (subdomain-based PSI), consisting of a username and a subdomain. Example: 3pty@factory.operator.net

mtas3ptyFactoryUri

For more information about the 3PTY attributes, refer to Managed Object Model (MOM).

3.2   3PTY Administrative State Configuration

The 3PTY service is enabled by setting the mtas3ptyAdministrativeState attribute in the Mtas3pty MO to 1 (Unlocked). If the mtas3ptyAdministrativeState is set to 0 (Locked), no 3PTY service is provided by the MTAS.

3.3   Wholesale for 3PTY Configuration

The 3PTY service supports Wholesale. 3PTY is configurable on Virtual Telephony Provider level.

Wholesale for 3PTY is activated when the following attributes are set to 1 (Unlocked):

For more information about the Wholesale service, refer to MTAS Wholesale Support Management Guide.

3.4   Service Data Configuration

This section describes how to configure the service data.

3.4.1   Operator Subscription Level Service Configuration

In the 3PTY configuration data for a subscriber, the operator indicates whether the subscriber is allowed to create the 3PTY session through the CAI3G protocol, refer to MTAS CAI3G Interface.

3.4.2   Subscriber Subscription Level Service Configuration

No service data for the 3PTY service is configured in the subscriber part of the subscriber data.

4   Performance Management

Measurements related to the 3PTY services are detailed in Managed Object Model (MOM).

5   Fault Management

The 3PTY service has no alarms.



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