In a modern Avaya Aura® Contact Centre (AACC) environment, agent desktops are typically SIP-based endpoints, such as Avaya Agent for Desktop. For these SIP agents, Application Enablement Services (AES) provides Computer Telephony Integration (CTI) by communicating with Avaya Aura® Session Manager, not directly with Communication Manager (CM) for call events. The standard-based protocol used for this communication between AES and Session Manager is TR/87, which specifies CSTA (Computer Supported Telecommunications Applications) over SIP. Session Manager then communicates with CM to control the call. Therefore, within the message flow for an AACC SIP agent, TR/87 is the essential CTI protocol used by AES.

A. WCF: Windows Communication Foundation (WCF) is a Microsoft programming framework and not a telephony signaling or CTI protocol used between Avaya Aura® core components.

B. ASAI/TSAPI: The ASAI (Adjunct/Switch Application Interface) protocol is used for the direct CTI link between AES and CM. However, this link is primarily for controlling non-SIP (e.g., H.323/DCP) endpoints, not for the modern AACC SIP agent architecture.

C. DMCC/TSAPI: DMCC (Device, Media, and Call Control) is a service used by AES for controlling endpoint devices and media streams, such as the AACC softphone client, but it is not the primary protocol for call-state event signaling.

1. Avaya Aura® Contact Center Solution Description (NN43001-109, Issue 11.0, July 2017):

Page 26, Section: Avaya Aura® Application Enablement Services: "For SIP agent support, Application Enablement Services uses the TR/87 protocol to communicate with Session Manager." This document explicitly states that TR/87 is the protocol used for SIP agents in an AACC context.

2. Avaya Aura® Application Enablement Services Overview and Specification (02-300360, Issue 11, May 2017):

Page 11, Section: CSTA Service: "The CSTA service provides an ECMA-323 CSTA Phase III XML interface that is compliant with the TR/87 standard from the SIP Forum... The CSTA service uses the TR/87 standard to communicate with Avaya Aura® Session Manager." This confirms AES uses TR/87 to communicate with Session Manager.

3. Application Notes for configuring Avaya Aura® Contact Center 7.0.2 with Avaya Aura® Communication Manager 7.1, Avaya Aura® Session Manager 7.1 and Avaya Aura® Application Enablement Services 7.1 (May 2017):

Page 4, Figure 1: Avaya Aura® Contact Center with Avaya Aura® - System Architecture: The system architecture diagram clearly illustrates a communication link labeled "TR87" between the Application Enablement Services server and the Session Manager. This visual evidence from an official configuration guide reinforces the protocol's role in the message flow.

The 8D Troubleshooting Methodology is a sequential problem-solving process. After Discipline 4, where the root cause of the problem is identified and verified, the team proceeds to Discipline 5. The primary purpose of Discipline 5 is to brainstorm, evaluate, and select the most effective permanent corrective action(s) to eliminate the identified root cause. This step focuses on choosing the optimal solution before it is implemented, ensuring it will be effective and will not introduce new problems. The implementation itself occurs in the subsequent discipline, D6.

A. Discipline 5 – Implement a Work-around: Implementing a work-around or interim containment action is the purpose of Discipline 3, not Discipline 5.

B. Discipline 5 – Implement Corrective Actions: The implementation of the permanent corrective actions is performed in Discipline 6, after they have been chosen and verified in Discipline 5.

D. Discipline 5 – Prevent Recurrences: Preventing the problem from recurring is the objective of Discipline 7, which involves standardizing the changes and updating systems and procedures.

1. Avaya Professional Services. (2009). Avaya Tier 3+ Problem and Incident Management Process Description (Document ID: PIMProcessR3.0Issue1.0). Section 4.6, "D5: Choose and Verify Corrective Action," p. 14. This official document states, "The purpose of this step is to select the best permanent corrective action to remove the root cause and to verify that the decision will be successful."

2. University of Washington, Department of Mechanical Engineering. (n.d.). ME 495: Introduction to Mechanical Design - 8D Problem Solving. Lecture Slides. Slide 11, "The 8 Disciplines," lists the step following D4 (Determine Root Cause) as "D5: Develop/Choose Permanent Corrective Action(s) (PCA)."

Avaya Aura® Contact Center (AACC) integrates with Avaya Aura® Communication Manager via Application Enablement Services (AES). The core protocol for this Computer Telephony Integration (CTI) link is the Telephony Services Application Programming Interface (TSAPI). The AACC server establishes a persistent TSAPI connection to the AES server. This connection allows AACC to monitor agent extensions, receive call events, and execute third-party call control functions (e.g., answer, hold, transfer), which are fundamental for contact center operations and are reflected on the agent's desktop application.

A. WCF: Windows Communication Foundation (WCF) is a Microsoft framework for building applications; it is not the specific CTI protocol used for AACC-to-AES communication.

C. TR/87: While AES supports TR/87 for web services-based CTI, AACC's primary and foundational CTI integration for server-based call control relies on the stateful TSAPI protocol.

D. DMCC: Device, Media, and Call Control (DMCC) is used for first-party call control, typically for softphone applications to control a specific device and its media stream, not for the server-level third-party call control that AACC requires.

1. Avaya Aura® Contact Center - Solution Description (NN42001-110, Issue 11.01, June 2017): In the "Avaya Aura® Contact Center CTI service" section, it states, "The CTI service uses a Telephony Services Application Programming Interface (TSAPI) link to Avaya Aura® Application Enablement Services to provide telephony integration with Communication Manager." (See Chapter 2: Architecture, Page 2-10).

2. Avaya Aura® Application Enablement Services Overview and Specification (02-300363, Issue 11.0, November 2016): This document describes the services offered by AES. In the section on TSAPI Service, it details its function for third-party call control, which is the model used by applications like AACC. It explicitly lists "Contact Center" as a primary application type for the TSAPI service. (See Chapter 2: AE Services, Section: TSAPI Service).

3. Implementing Avaya Aura® Contact Center (7.0), Course Number 72301C, Student Guide: The course material on AACC architecture consistently depicts the Communication Control Toolkit (CCT) server component of AACC connecting to AES via a TSAPI link for CTI messaging. (Module: AACC Architecture).

The Avaya Diagnostic Methodology (ADM) is an 8-step structured troubleshooting process. The question states that the first three steps (State the Problem, Detail the Findings, Clarify the Problem) have been completed by the customer or partner. The subsequent steps performed by Avaya support involve identifying the root cause and then implementing a solution. Since "Identify the Root Cause" is not provided as an option, the next logical phase in the resolution process from the choices available is "Implement a solution." This step is central to resolving the reported issue before it can be verified and documented.

A. Install a patch to fix the problem.

This is a specific type of solution. The general step is to "Implement a solution," which could also involve a configuration change or other corrective actions.

B. Praise individuals for contribution.

This is the final step (Step 8) in the ADM process, which occurs after the problem has been fully resolved, verified, and documented.

D. Update the Knowledge Management database.

This is Step 7 of the ADM process, performed after a solution has been implemented and successfully verified (Step 6), but before the final step.

1. Avaya Learning, Course 7230XCT, Avaya Aura® Communication Manager and CM Messaging - Embedded Maintenance and Troubleshooting.

Reference: Module on "Avaya Diagnostic Methodology (ADM)". This courseware details the 8-step ADM process, clearly placing "Implement a Solution" as Step 5, which follows the initial problem definition and root cause analysis phases.

2. Official Avaya Partner Training Materials on Avaya Diagnostic Methodology (ADM).

Reference: "Avaya Diagnostic Methodology for BusinessPartners" guide, Section: "The 8 Steps of ADM". The document lists the sequential steps as: 1. State the Problem, 2. Detail the Findings, 3. Clarify the Problem, 4. Identify the Root Cause, 5. Implement a Solution, 6. Verify the Solution, 7. Update Knowledge Management, 8. Praise Individuals. This confirms that implementing a solution is the next major phase after the initial data gathering and analysis.

Avaya Aura® Messaging (AAM) is a flexible messaging platform that supports various deployment models and configurations. It can be deployed in a virtualized environment using VMware or on Avaya's proprietary System Platform, providing deployment flexibility (B). A core feature of its unified messaging capability is the choice of message store; administrators can select either the integrated Avaya Message Store (AMS) or an external Microsoft Exchange server to store voice messages (C). For scalability and high availability, AAM supports a multi-server (distributed) configuration where the Application Server (handling call processing) is logically and physically separated from the server hosting the Avaya Message Store (D).

A. Port allocation in AAM is configurable and dynamic based on system needs; there is no fixed, mandatory reservation of 20 ports specifically for retrieving messages.

E. An Avaya Aura® Messaging application server supports up to 300 simultaneous SIP or H.323 sessions, not 100. The figure of 100 sessions per server is incorrect.

1. Avaya Aura® Messaging Overview and Specification, Release 7.1 (Document ID: 03-603836, Issue 10, September 2017)

For B: Page 10, Section "Deployment options," states, "Avaya Aura® Messaging can be deployed as a virtualized application on VMware vSphere ESXi... Messaging can also be deployed on System Platform."

For C: Page 12, Section "Message storage," details the two options: "Avaya Message Store (AMS)" and "Microsoft Exchange Server."

For E: Page 15, Table 3 "Avaya Aura® Messaging capacities," specifies "Maximum number of voice ports per application server" as "300."

2. Planning for Avaya Aura® Messaging, Release 7.1 (Document ID: 16-603837, Issue 10, September 2017)

For D: Page 18, Section "Distributed configuration," describes the architecture: "In a distributed configuration, you can have one or more Application servers and one or more Storage servers." This confirms the separation of roles.