MTAS Call Return Management Guide

MTAS

1	Introduction
1.1	Prerequisites
2	Overview
2.1	Subfunctions
2.2	Interaction with Other Services
3	Call Return Service Configuration
3.1	Call Return Administrative State Configuration
3.2	Configuration Activities
3.3	Announcement Configuration
3.4	Wholesale for Call Return Configuration
3.5	Auto Call Back Configuration
3.6	Service Data Configuration
4	Performance Management
5	Fault Management

1 Introduction

This document describes how to configure the Call Return service in the MTAS.

1.1 Prerequisites

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

1.1.1 Licenses

To enable the Call Return service, the Call Return license must be installed.

For more information about the Call Return 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

The Call Return service saves information (such as tel URI and SIP URI) about the last incoming call and provides the end user with the possibility to obtain this information using a Supplementary Service Code (SSC). The user can also call back to the user of the incoming call.

The Call Return service mainly consists of two parts, saving of the last incoming call and invocation of Call Return.

2.1 Subfunctions

The subfunctions included in the Call Return service are described in this section.

2.1.1 Saving Last Incoming Call

The Call Return service can be configured to be triggered by either all calls or by unanswered calls only. The last incoming call is saved by the terminating MTAS. The detection of a last incoming call occurs when a "180 Ringing" is received (if Call Return is configured to all calls) or if no "200 OK" is received at the terminating MTAS from the called user (if Call Return is configured to unanswered calls).

The last saved incoming call is kept by the MTAS until either a new incoming call is received or the user is deregistered. During this time, the user can use the Call Return service to make a callback to the caller at any time.

2.1.2 Start Call Return

The served user can make a callback to the caller of the last incoming call by using the SSC in the initial INVITE message, as follows:

The served user receives an incoming call. The call data is stored.
The served user dials the SSC for Call Return. There is one SSC for Call Return without announcement prompt and one SSC for Call Return with announcement prompt.
If the SSC for Call Return without announcement prompt is dialed, a call attempt is made to the caller of the last saved incoming call.
Alternatively, if the SSC for Call Return with announcement prompt is dialed, the served user is presented with an announcement detailing the last incoming call phone number, date/time, and the call return code. The date is included in the announcement when the invocation day is not the same day as when the call is saved, otherwise the time is included.

If there is no last incoming call or the last incoming call includes a privacy header, the served user is informed so with an announcement and the Call Return fails.

2.1.3 Play Announcement

To play announcements to the served user, the announcement function in the Media Resource Function Processor (MRFP) is used.

2.1.4 Play Collect

The Play Collect function uses an MRFP to play the segment variable announcement to the served user and collect Dual-Tone Multifrequency (DTMF) digit from the served user.

The Call Return service is rejected when it is not possible to play the segmented variable announcements, collect digits, or when faulty digits are collected.

2.1.5 Charging for Call Return

Multimedia Telephony (MMTel) sessions that use the Call Return service support charging. The Credit Control Request (CCR), Initial Request, and Accounting-Request (ACR) Start generated by the originating MTAS on which Call Return was started, include the following Attribute-Value Pairs (AVPs) within the MMT Information AVP:

Supplementary-Service-Information (group)
Supplementary-Service-Identity
Set to "Call Return without announcement prompt" or "Call Return with announcement prompt".
Supplementary-Service-Action
Set to "Use of Service".

For more information about offline and online charging, refer to the following documents:

2.2 Interaction with Other Services

This section describes the Call Return interactions with other services.

2.2.1 Anonymous Callers

When the served user receives a call from an anonymous caller, the call is saved as the last call. When the served user starts Call Return, an announcement is played informing the served user that the last incoming call was private or anonymous.

2.2.2 SSC

When the auto callback function is started, the called user dials the SSCs for Call Return, one SSC for Call Return without announcement prompt, and one SSC for Call Return with announcement prompt.

3 Call Return Service Configuration

The Call Return service is controlled by the MtasCr MO. An overview of the Call Return MO structure is shown in Figure 1.

Figure 1 Call Return MO Structure

For configurable MOs and attributes related to the Call Return service, refer to Managed Object Model (MOM).

3.1 Call Return Administrative State Configuration

The Call Return service is enabled by setting the mtasCrAdministrativeState attribute in the MtasCr MO to 1 (Unlocked). If the mtasCrAdministrativeState is set to 0 (Locked), no Call Return service is provided by the MTAS.

3.2 Configuration Activities

The configuration activities are listed in Table 1.

Table 1 Additional Configuration Activities
Activity	Attribute
Defines if the last incoming call or the last unanswered incoming call is to be saved (0=last call, 1=last unanswered call).	`mtasCrSaveUnansweredCall`
Defines the value of the operator named announcement to be played when the Call Return service rejects an attempt when no saved call for the served user exists.	`mtasCrNoSavedCallAnnName`
Defines the value of the operator named announcement to be played when the Call Return (CR) service rejects an attempt when the saved call includes privacy header.	`mtasCrPrivacyCallSavedAnnName`
Defines the value of the operator named segmented announcement to be played when the Call Return service prompts the caller with information about the code to press for making a call return.	`mtasCrNoPhonePromptAnnName`
Defines the value of the operator named segmented announcement to be played when the Call Return service prompts the caller with information about the last call and the code to press for making a call return.	`mtasCrPromptAnnName`
Defines the code to press to make a callback call when started with the supplementary service code for Call Return with announcement prompt.	`mtasCrCallReturnCode`
Defines the auto callback timer for the Call Return service when started with the supplementary service code for Call Return without announcement prompt and the `mtasCrAutoAnnName` is configured.	`mtasCrAutoCallBackTimer`
Defines the Call Return time to wait for the first digit in the `mtasCrCallReturnCode` after the announcement (`mtasCrPromptAnnName` or `mtasCrNoPhonePromptAnnName`) is finished.	`mtasCrFirstDigitTimeout`
Defines the Call Return time between the digits in the `mtasCrCallReturnCode` after the announcement (`mtasCrPromptAnnName` or `mtasCrNoPhonePromptAnnName`) is finished.	`mtasCrInterDigitTimeout`
Defines the value of the operator named segmented announcement to be played when the Call Return is started with the supplementary service code for Call Return without announcement prompt.	`mtasCrAutoAnnName`

3.3 Announcement Configuration

When the Call Return service is started with the service code for call return without announcement prompt mtasSscCrComSyntInv, the default setting is that no announcement is played and controlled by the mtasCrAutoAnnName attribute. This attribute is empty by default. If an announcement is to be played, an announcement name, that is, the announcement named by the operator, must be set.

When the Call Return service is started with the service code for call return with announcement prompt mtasSscCrAnnComSyntInv, the default setting is that the announcement is played and controlled by the mtasCrPromptAnnName and mtasCrNoPhonePromptAnnName attributes. These attributes are by default empty. If an announcement is to be played, an announcement name, that is, the announcement named by the operator, must be set.

For information on announcement handling and Call Return announcement attributes, refer to MTAS Announcement Management Guide.

An example of announcement configuration for Call Return is shown in Example 1:

Example 1 Configuring mtasCrPromptAnnName to Play "Your last call was from xxx at yyyymmdd/hhmm to callback press zz"

This is the structure of a segmented announcement. 
1300 = "Your last call was from" (fix part)
LastCall =="xxx" variable part (phone number)
2000 = "at" (fix part)
LastCallDate = "yyyymmdd" optional variable part(date)
LastCallTime = "hhmm" optional variable part(tod)
1500 = "to callback press" (fix part)
InvokeCode = "zz" variable part (mtasCrCallReturnCode = zz)

3.4 Wholesale for Call Return Configuration

The Call Return service supports Wholesale. Call Return is configurable on Virtual Telephony Provider-level.

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

The vtasCrAdministrativeState attribute in the VtasCr MO
The mtasCrAdministrativeState attribute in the MtasCr MO

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

An example of a CAI3G protocol of how to provision Call Return is shown in Example 2.

Example 2 CAI3G Protocol of Call Return Provisioning

<?xml
  version="1.0"
  encoding=UTF-8"
  ?>
<Sh-Data
  xmlns:xsi="http.//www.w3.rog/2001/XMLSchema-instance"
  xsi:noNamespaceSchemaLocation="mtas-sh-top-schema.xsd">
  <RepositoryData>
    <ServiceIndication>
      MmtServiceConfig
    </ServiceIndication>
    <SequenceNumber>
      0
    </SequenceNumber>
    <ServiceData>
      <mmt-data:telephony-service-configuration
        version="3.1"
        xmlns:cp="urn:ietf:params:xml:ns:common-policy"
        xmlns:mmt-data="http://schema.ericsson.com/mmtel/service-data"
        xmlns:mmt-op="http://schema.ericsson.com/mmtel/operator-service-data"
        xmlns:mmt-serv="http://schemas.ericsson.com/mmtel/services"
        xmlns:ocp="urn:oma:xml:xdm:common-policy"
        xmlns:ss="http://uri.etsi.org/ngn/params/xml/simservs/xcap">
        <mmt-data:user-configuration>
          <ss:simservs/>
        </mmt-data:user-configuration>
        <mmt-data:operator-configuraion>
          <mmt-data:operator-service-data>
            <mmt-op:operator-call-return
              activated="true"/>  
          </mmt-data:operator-service-data>
        </mmt-data:operator-configuraion>
      </mmt-data:telephony-service-configuration>
    </ServiceData>
  </RepositoryData> 
</Sh-Data>

3.6.2 Subscriber Subscription Level Service Configuration

No service data for the Call Return service is configured in the subscriber part of the subscriber data.

4 Performance Management

For measurements related to the Call Return service, refer to Managed Object Model (MOM).

5 Fault Management

For alarms related to the Call Return service, refer to MTAS Alarm List.