Adamster2-7707 avatar image
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Adamster2-7707 asked Adamster2-7707 answered

Teams, Exchange and Cloud


First thank you in advance for all your help. I am a beginner when it comes to cloud so not familiar with it at all so some of my questions will seem basic so please be patient.

The organization (very small) I currently work for have currently no cloud presence and is somewhat hesitant in going that route. We currently have:

  • On Prem - Exchange Server 2016 CU19 Apr21SU Version 15.1.2176.12

  • Microsoft Teams Exploratory Licenses

  • On Prem - Active Directory

We recently started testing Microsoft Teams. We have a group of people 5 to 10 users that signed up on Teams using account as a work account. 1 user out of those 10 is an Admin for the company which is me for now. The following are the issues that we have noticed so far:

  • Users are not able to see the calendar tab in teams.

  • For those users that do see the calendar app, their calendar is not syncing with their outlook (exchange) mailbox.

We would like use Teams and have the calendar merge with our exchange. I tried doing some research and also called Microsoft, however I have not been able to get a clear answer to what exact step by step items I need to do in order to make this happen. I have access to our Microsoft 365 Admin Portal, Teams Admin Portal. I also see some licenses for Exchange Online.

Some of the research started guiding me towards AD Active Sync and Exchange Sync but I am not sure what that would mean and how to actually go about doing this. Would someone please try to help me understand this.

One last thing, if you do recommend something, please also let me know if there would be an extra cost associated with it or if that is available as part of O365, Exchange Online, or Teams.

Thanks Again!

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Adamster2-7707 avatar image
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Adamster2-7707 answered

Although provided guidance, none of the answers above answered the question in its entirety. The link that was sent was already looked at as part of my research.

I will take an attempt at answering my own question:

Full features of Teams can be utilized only after successful Exchange Hybrid Configuration and Azure AD Sync. This will enable two features that the question was related to: centralized account management and Calendar Synchronization with on Prem Exchange. Below is what was gathered as steps and prerequisites for these features to be enabled:

Exchange Hybrid Configuration & AD Sync is free

One Prerequisite for Exchange Hybrid is AD Azure Sync

AD Azure Sync prerequisite is following:

1) Azure Subscription - Not required if already on O365
2) Make sure Azure AD connect server is at least 2008 R2 SP1
3) Azure AD connect Server must have .Net Framework 4.5.1 or later

For all other requirement use link:

Other Prerequisites for Exchange Hybrid are:

1) Exchange 2016 or newer
2) Microsoft 365 / O365 (Any subscription)
3) Custom Domains - (Email)
4) AD Synchronization
5) Auto discover DNS Records
6) Microsoft 365 or Office 365 in the Exchange Admin Center (EAC)
7) Public Certificate -
8) EdgeSync - Not applicable if company do not have an Edge Transport Server
9) Microsoft .Net Framework 4.6.2 on the server that runs Hybrid Configuration Wizard
10) Firewall Exceptions
10A) For Exchange and AD connect to work, many IP addresses, ports and URLs must be whitelisted on the firewall. A list of what needs to be excluded can be found on the website below:

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michev avatar image
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michev answered SharonZhao-MSFT commented

Teams is a cloud-born application and thus it works best when you're using Exchange Online/SharePoint Online. It will work with on-premises Exchange too, but there are some caveats/additional configuration needed. Refer to this article and the references therein for additional details:
Generally speaking, most small organizations should have no problem switching to O365, and might even enjoy some cost savings as part of it.

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Agree with michev. According to your description, it seems that you don’t deploy hybrid between your on-premises Exchange server and Office 365.

There are several requirements to create and view meetings in Teams client for mailboxes hosted on-premises:

  • The Teams license needs to be assigned for the Azure Active Directory synced user

  • Users must be synchronized to Azure Active Directory

  • Mailboxes are hosted in Exchange Server 2016 Cumulative Update 3 or later

  • Autodiscover and Exchange Web Services is published externally

  • OAuth authentication is configured via the Exchange Hybrid Configuration Wizard running a full hybrid configuration

  • The checkbox for the Exchange Hybrid Deployment feature in Azure AD Connect is set.

  • Exchange Web Service URLs must be configured as SPNs in Tenant Azure AD for the Exchange Service Principal.

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