https://docs.microsoft.com/en-us/microsoft-365/admin/add-users/about-admin-roles?view=o365-worldwide

According to the Microsoft documentation1, you need to add an emergency address for each location where your users make and receive phone calls. An emergency address is a civic address-the physical or street address of a place of business for your organization. It is used to route emergency calls to the appropriate dispatch authorities and to assist in locating the emergency caller.
After you add an emergency address, you need to assign a phone number to it. You can assign either a user number or a service number. A user number is assigned to a specific user in your organization who makes and receives phone calls. A service number is used for services such as Audio Conferencing (for dial-in numbers), auto attendants, or call queues.
To assign a phone number to an emergency address, you need to modify the location for each phone number. You can do this by using the Microsoft Teams admin center or PowerShell. For example, to modify the location for a user number by using PowerShell, you can use the Set-CsOnlineVoiceUser cmdlet with the -LocationID parameter2.
Topic 2, Contoso, Ltd
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Overview
Contoso, Ltd. is a pharmaceutical company that has 3,000 users in offices across North America.
Existing Environment
Active Directory
The network contains an on-premises Active Directory domain. All user accounts are in departmental organizational units (OUs).
Microsoft Office 365
All users are assigned a Microsoft Office 365 E5 license and are enabled for the following services:
Microsoft Yammer
Microsoft Exchange Online
Microsoft SharePoint Online
Microsoft OneDrive for Business
Azure Active Directory (Azure AD)
Azure AD
dynamic group membership
Microsoft Skype for Business
Contoso has an on-premises deployment of Microsoft Skype for Business Server 2015. All the latest cumulative updates are installed on all the servers. The following services are used in Skype for Business Server 2015:
Meetings
PSTN calling
Instant messaging (IM)
Federation to external companies
Departments
Contoso has the following departments:
IT
Sales
Human resources (HR)
Research and deployment (R&D)
All groups are created by using dynamic group membership that use the department attribute.
Requirements
Business goals
Contoso identifies the following business goals:
Migrate the maximum number of users to Microsoft Teams.
Minimize administrative effort.
Device Requirements
Contoso identifies the following device requirements:
Replace Skype for Business IP phones with Microsoft Teams phones.
All Microsoft Teams phones must be set to lock automatically after 60 seconds.
Meeting and Live Event Requirements
Contoso identifies the following meeting and live event requirements:
Requirement1: Guest users must be able to join live events.
Requirement2: Guest users must always wait in a meeting lobby.
Requirement3: Contoso users must always bypass the meeting lobby when they join by using the Microsoft Teams client.
Requirement4: After the upgrade to Microsoft Teams, all meetings must be scheduled by using Microsoft Teams.
Calling Requirements
Contoso identifies the following calling requirements:
Migrate all existing auto attendants and response groups to Office 365.
Minimize the on-premises PSTN infrastructure.
Technical Requirements
Guest users must be prevented from making private calls.
Security Requirements
Contoso has the following security requirements for the Microsoft Teams deployment:
The number of ports allowed on the company's firewall must be limited.
Team names must be prevented from containing the name of any products produced by Contoso.
Users in the R&D group must be prevented from sending chat messages to users in other departments.
To meet the company's compliance policy, users in the sales department must continue to use on-premises Skype for Business for IM and calling only.
Pilot Project
Contoso begins a pilot project for the upgrade to Microsoft Teams.
You identify the following issues during the pilot project:
Microsoft Teams users report that they often receive continuous notifications from the Microsoft Teams client for 20 minutes.
Two pilot users in the HR department report that they are not members of the HR team.