00 — Teams Voice & Communications Fundamentals

Based on: Microsoft Teams Admin Documentation

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🗺 Overview

mindmap
  root((Voice & Comms Fundamentals))
    Teams Phone Architecture
      Cloud PBX
      PSTN Connectivity
      SBC / Direct Routing
      Operator Connect
      Calling Plans
    Meeting Infrastructure
      Meetings
      Webinars
      Town Halls
      Audio Conferencing
      Teams Premium
    Teams Rooms
      Windows Platform
      Android Platform
      Resource Accounts
      Peripherals
    Licensing
      Teams Phone Standard
      Calling Plans
      Audio Conferencing
      Teams Rooms Basic/Pro
      Teams Premium
      Communication Credits
    Admin Portals
      Teams Admin Center
      M365 Admin Center
      Entra Admin Center
      Call Quality Dashboard
    Network Fundamentals
      Ports & Protocols
      QoS
      Media Optimization
      Network Assessment

🏗️ Teams Phone Architecture

How Teams Phone Works

Microsoft Teams Phone is a cloud-based PBX (Private Branch Exchange) that replaces traditional on-premises phone systems. It provides calling capabilities within Teams using Microsoft’s cloud infrastructure.

Component	Purpose
Teams Phone System	Cloud PBX — call control, voicemail, auto attendants, call queues
PSTN Connectivity	Connects Teams Phone to the public telephone network
Session Border Controller (SBC)	Gateway between Teams and PSTN for Direct Routing
Auto Attendants	Automated call routing menus (IVR)
Call Queues	Hold and distribute calls to groups of agents
Cloud Voicemail	Voicemail with transcription, stored in Exchange Online

flowchart TD
    USER["Teams User"]
    PHONE["Teams Phone\n(Cloud PBX)"]
    CP["Microsoft\nCalling Plans"]
    OC["Operator\nConnect"]
    DR["Direct Routing\n(SBC)"]
    PSTN["PSTN\n(Public Network)"]

    USER --> PHONE
    PHONE --> CP --> PSTN
    PHONE --> OC --> PSTN
    PHONE --> DR --> PSTN

⚠️ Exam Caveat:

Teams Phone is the cloud PBX component — it does NOT include PSTN connectivity by itself

PSTN connectivity must be added separately via Calling Plans, Operator Connect, or Direct Routing

Teams Phone Mobile allows a user’s SIM-enabled mobile number to be their Teams phone number

📞 PSTN Connectivity Options

Option	Description	SBC Required?	Microsoft Manages PSTN?
Microsoft Calling Plans	Microsoft provides phone numbers and PSTN connectivity	No	Yes
Operator Connect	Telco operator provides PSTN via Microsoft-certified integration	No (operator-managed)	No
Direct Routing	Organization connects its own SBC to Teams Phone	Yes	No
Teams Phone Mobile	Mobile carrier provides PSTN via SIM-based number	No	No

flowchart LR
    subgraph "Microsoft Managed"
        CP["Calling Plans\n✅ Simplest\n❌ Limited countries"]
    end
    subgraph "Operator Managed"
        OC["Operator Connect\n✅ Carrier integration\n✅ Managed SBCs"]
        TPM["Teams Phone Mobile\n✅ SIM-based\n✅ Single number"]
    end
    subgraph "Customer Managed"
        DR["Direct Routing\n✅ Full control\n❌ SBC required"]
    end

⚠️ Exam Caveat:

Calling Plans are the simplest option but only available in specific countries

Direct Routing gives the most flexibility but requires an SBC and more complex configuration

Operator Connect is a middle ground — the operator manages the SBC infrastructure

Organizations can mix connectivity methods — e.g., Calling Plans for one region and Direct Routing for another

🎥 Meeting Types in Teams

Meeting Type	Audience	Max Attendees	Key Features
Meeting	Internal/external collaboration	1,000 (up to 20,000 in view-only)	Breakout rooms, recording, transcription, Copilot
Webinar	Structured presentations with registration	1,000	Registration, presenter/attendee roles, engagement reports
Town Hall	Large-scale broadcast events	10,000 (up to 20,000 with Teams Premium)	Q&A, eCDN support, producer controls
Virtual Appointment	External customer-facing meetings	Varies	SMS notifications, waiting room, custom branding

⚠️ Exam Caveat:

Webinars support registration and structured presenter roles — meetings do not

Town halls replace the legacy Live Events feature

Teams Premium extends capacity and adds advanced features (custom branding, watermarks, Copilot in meetings)

Audio Conferencing adds dial-in numbers to any meeting type

📜 Licensing Overview

Core Licenses for Teams Phone

License	What It Provides
Teams Phone Standard	Cloud PBX — auto attendants, call queues, voicemail, call park, transfer
Microsoft Calling Plan (Domestic/International)	PSTN connectivity and phone numbers via Microsoft
Operator Connect	PSTN via certified operator (operator provides license/numbers)
Communication Credits	Pay-per-minute for toll-free numbers and international dial-out

Plans That Include Teams Phone

Plan	Teams Phone Included?	Audio Conferencing Included?
Microsoft 365 E5	Yes	Yes
Microsoft 365 E3	No — add Teams Phone Standard	No — add separately
Microsoft 365 E1	No — add Teams Phone Standard	No — add separately
Microsoft 365 Business Premium	No — add Teams Phone Standard	No — add separately
Microsoft 365 F1/F3	No — add Teams Phone Standard	No — add separately

Teams Rooms Licensing

License	Features
Teams Rooms Basic	Free for up to 25 rooms — join meetings, screen sharing, whiteboard
Teams Rooms Pro	Unlimited rooms — remote management, advanced analytics, Intune enrollment, Copilot

⚠️ Exam Caveat:

M365 E5 is the only standard plan that includes both Teams Phone and Audio Conferencing

Teams Rooms Basic is limited to 25 rooms per tenant — beyond that, you need Teams Rooms Pro

Resource accounts for auto attendants/call queues need a Teams Phone Resource Account license (free) plus a Calling Plan or virtual user license if they need a phone number

Communication Credits are required for toll-free Audio Conferencing dial-in numbers

🖥️ Admin Portals

Portal	URL	Primary Use for MS-721
Teams Admin Center	admin.teams.microsoft.com	Phone policies, meeting policies, device management, auto attendants, call queues
M365 Admin Center	admin.microsoft.com	User/license management, service health
Microsoft Entra Admin Center	entra.microsoft.com	Identity, Conditional Access, resource account management
Call Quality Dashboard (CQD)	cqd.teams.microsoft.com	Tenant-wide call quality analytics and reporting
Teams Rooms Pro Management	portal.rooms.microsoft.com	Teams Rooms monitoring, alerts, and remote management
Microsoft Intune	intune.microsoft.com	Device compliance, configuration profiles for Teams devices

⚠️ Exam Caveat:

Call Analytics (per-user) is accessed from the Teams Admin Center under Users

Call Quality Dashboard (tenant-wide) is a separate portal at cqd.teams.microsoft.com

Teams Rooms Pro Management portal requires a Teams Rooms Pro license

Phone number management is done in the Teams Admin Center under Voice > Phone numbers

👤 Relevant Admin Roles

Role	Scope
Teams Administrator	Full access to Teams admin center — all Teams settings, policies, and devices
Teams Communications Administrator	Manages calling and meeting features — voice, phone numbers, meeting policies
Teams Communications Support Engineer	Access to advanced call analytics — all users, full telemetry
Teams Communications Support Specialist	Access to basic call analytics — per-user only
Teams Devices Administrator	Manages Teams device configuration and profiles
Global Administrator	Full access to everything (use sparingly — least-privilege principle)

⚠️ Exam Caveat:

Teams Communications Administrator can manage phone numbers, calling policies, and meeting settings

Teams Devices Administrator can manage device configuration but cannot change calling or meeting policies

The exam frequently tests least-privilege — choose the most restrictive role that can complete the task

🔧 PowerShell for Teams Phone

Key Cmdlets

# Install the module
Install-Module -Name MicrosoftTeams -Force

# Connect
Connect-MicrosoftTeams

# Phone number management
Get-CsPhoneNumberAssignment
Set-CsPhoneNumberAssignment -Identity user@domain.com -PhoneNumber "+14255551234" -PhoneNumberType DirectRouting

# Calling policies
Get-CsTeamsCallingPolicy
New-CsTeamsCallingPolicy -Identity "RestrictedCalling" -AllowPrivateCalling $true
Grant-CsTeamsCallingPolicy -Identity user@domain.com -PolicyName "RestrictedCalling"

# Auto attendants and call queues
Get-CsAutoAttendant
Get-CsCallQueue
New-CsOnlineApplicationInstance -UserPrincipalName aa@domain.com -DisplayName "Main Auto Attendant" -ApplicationId "ce933385-9390-45d1-9512-c8d228074e07"

# Direct Routing
Get-CsOnlinePSTNGateway
New-CsOnlinePSTNGateway -Fqdn "sbc.domain.com" -SipSignalingPort 5061 -Enabled $true
Get-CsOnlineVoiceRoute
Get-CsOnlineVoiceRoutingPolicy

Application IDs

Application	Application ID
Auto Attendant	`ce933385-9390-45d1-9512-c8d228074e07`
Call Queue	`11cd3e2e-fccb-42ad-ad00-878b93575e07`

⚠️ Exam Caveat:

PowerShell is required for bulk phone number assignments and advanced Direct Routing configuration

Resource accounts (application instances) use specific Application IDs — auto attendant and call queue have different IDs

Set-CsPhoneNumberAssignment replaces the deprecated Set-CsUser for phone number assignment

🌐 Network Fundamentals for Teams Voice

Key Ports and Protocols

Protocol	Port Range	Purpose
HTTPS	TCP 443	Signaling, authentication, API calls
STUN/TURN	UDP 3478	Media relay — NAT traversal
Media	UDP 3479–3481	Audio, video, screen sharing
SIP	TCP/TLS 5061	Direct Routing SBC signaling

Bandwidth Requirements (Per User)

Scenario	Minimum Bandwidth
Audio call (1:1)	~30 kbps
Video call (1:1, 720p)	~1.5 Mbps
Video call (1:1, 1080p)	~2.5 Mbps
Screen sharing	~200 kbps
Large meeting (video gallery)	~2.5–4 Mbps

Quality of Service (QoS)

Media Type	Source Port Range	DSCP Value	DSCP Class
Audio	50000–50019	46	EF (Expedited Forwarding)
Video	50020–50039	34	AF41
App/Screen Sharing	50040–50059	18	AF21

⚠️ Exam Caveat:

UDP is preferred for real-time media — if blocked, Teams falls back to TCP 443 with degraded quality

Direct Routing SBCs connect to Teams via TLS on port 5061 — this is SIP signaling, not media

QoS DSCP marking is critical for prioritizing voice traffic — audio should always be EF (46)

Know the difference between Network Planner (capacity planning) and Network Assessment Tool (connectivity testing)

📚 Further Reading

Resource	Link
Teams Phone Overview	Teams Phone Documentation
PSTN Connectivity Options	PSTN Options
Teams Rooms Overview	Teams Rooms Docs
Network Readiness	Prepare Network for Teams
Teams Licensing	Teams Add-on Licensing

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