How to Connect Microsoft Teams and Slack in 2024

This post exists to answer the question: Does Microsoft Teams integrate with Slack?

We know chat must be native, seamless, and simple to administer. But with both Microsoft Teams and Slack dominating the team collaboration market,  enterprises using both apps need to connect Slack and Microsoft Teams.

Most notably, we hear from customers that were thinking about moving from Slack to Microsoft Teams or blocking Slack in favor of Microsoft Teams, and vice versa.

Does Microsoft teams integrate with Slack?

Rather than continue working in silos, we've highlighted six ways to connect Slack and Microsoft Teams.

1 - Use Mio’s message interop to connect Slack and Microsoft Teams

Using Mio’s message interoperability technology, you can sync channels and users within your organization. This enables cross-platform messages.

For example, when half your business uses Microsoft Teams and the other half uses Slack, you can connect the platforms in the background and let your users continue using their preferred platform.

No longer do they have to switch between apps to cater to colleagues who use a different platform. 

When you connect your platforms using Mio, every component of the message gets sent from Slack to Microsoft Teams.

This includes:

• Message edits
• Message deletions
• Channel messages
• Group messages
• GIFs and emojis
• File uploads
• Rich text formatting

Mio supports both channel conversations and direct messages within an organization. Whether you sync channels, direct messages, or both is up to you.

If you need to connect Slack and Microsoft Teams internally, message interop is the way to go.

Learn more about Mio here.

2 – Slack and Microsoft Teams calling integration

The integration between Slack and Microsoft Teams VoIP functionality arrived as part of a comprehensive update at Enterprise Connect, in April 2020. 

Pros: 

The update allows for Microsoft Teams calls to start through Slack. You can access the integration through the shortcuts button on Slack. This lightning-bolt-shaped icon near your message input field allows you to start a Teams call instantly. 

If you prefer the Slash command option on Slack, then you can opt for the /Teams-Calls to launch your Teams call from Slack instead. 

Cons: 

Unfortunately, the Slack and Teams calling integration is limited. It only connects one aspect of Slack and Microsoft Teams. 

You can start a call through Microsoft Teams in Slack this way, but you can’t send instant messages or send files from someone on Slack to someone on Teams. 

Tom Arbuthnot, Principal Solutions Architect at Modality Systems and Microsoft MVP, agrees the Slack and Teams calling integration is not a complete solution for connecting Slack and Microsoft Teams.

“The Slack “integration” to Microsoft Teams, while clever, is really just a Microsoft Teams meeting join link in Slack that fires up Microsoft Teams to join the Teams meeting.” 

Users often ask for further integration like being able to directly call or chat from one platform to another.

Team collaboration tools should allow access to a wide range of communication options. That makes the latest integration restrictive. After all, there’s a lot more to Slack and Microsoft Teams than just calling.  

In an interview for UC Today, Mio CEO, Tom Hadfield, commented on the news of the integration:

“The future of intercompany collaboration relies on full interoperability between Slack and Microsoft Teams. Cross-platform calling is a good start, but our customers tell us what they really need is cross-platform shared channels and direct messaging.”

3 – Configure webhooks for Slack & Microsoft Teams

Using Slack webhooks allows you to configure outcomes for different scenarios between your two platforms. If you’re the Slack admin, or at least familiar with the Slack API, the documentation available can guide you through simple setups.

Pros:

By using webhooks, you have a low-cost solution to a complex enterprise issue.

Webhooks also take little time to configure per scenario. If the issue exists in a single channel, webhooks are a good solution to a large-scale problem.

Cons:

The downside to using webhooks revolves around the amount of manual configuration required.

When you are dealing with multiple channels in an enterprise scenario, webhooks are simply not scalable.

They also don’t tend to display in a native way, and instead, from a bot.

End users have to re-train behavior in order to message cross-platform, and who has time for that? You? Didn’t think so.

In an organization of a few hundred or more, remembering who uses what platform becomes impossible to mentally track.

News also broke in April 2020 when it was discovered some Slack webhooks has been exposed as potential phishing hooks.

Researchers said there are nearly 131,000 Slack webhook URLs available on the Internet.

4 – Use APIs & bots to connect Slack & Microsoft Teams

Pros:

Bots for Slack and Microsoft Teams are on the rise. Bots can be leveraged to create a more native experience.

Microsoft publishes a Slack connector in its connector inventory that enables some Slack and Microsoft Teams crossover.

You will benefit from functionality like joining a Slack channel and can even set triggers for certain events.

However, limited functionality stops experiments pretty quickly. For example, direct messaging goes totally unmentioned.

Cons:

Most users, especially in the enterprise space, are still in the experimental phase in terms of users being comfortable using them.

One Github community working on a tool to connect Slack and Microsoft Teams expressed concerns that various API and migration tools are limited to basic functionality.

Most of these solutions are still configuration-based.

This means you will spend incredible time and resource making each channel work for you – and maintain this configuration as you add and modify channels.

5 – Create your own app using an app builder

Pros:

Generally, app builders are simple to use.

With a no-code approach, you don’t need to hire a specialist engineer to connect Slack and Microsoft Teams

You can get a free trial to play around with your requirements.

Most app builders support a wide range of apps to integrate like Slack, Google Sheets, and Trello.

Cons:

Functionality is limited by the supported features available on a particular app builder.

One user got in touch with Mio for a replacement solution to using an app builder stating:

“I tried an app builder but it was too limited. Threads didn’t work, and users name matching was absent. “

The functionality will also be limited by your own building skills and requirements gathering.

While support is available with most app builders, it is considered a DIY approach to connecting Slack and Microsoft Teams.

6 – Use the Microsoft Graph API to migrate Slack to Teams

Microsoft is working on a migration API to help IT managers and Microsoft admins migrate chats from Slack to Teams.

As of September 2020, Microsoft has made documentation available and certain tenants can sign up for the beta program.

In theory, Microsoft wants to allow Slack messages to be migrated over to Teams without a delay or break in service and/or conversation.

The in-scope and out-of-scope items are included below:

Pros:

Previous attempts to migrate Slack to Teams have resulted in a loss of historical data and messages. The new migration API changes that.

As Tom Morgan, Product Innovation Architect at Modality Systems, pointed out his blog, an organization might be moving from Slack to Teams but have 5+ years' worth of message history in Slack.

Previously, in this scenario, there have been workarounds that result in a disjointed and almost unworkable experience. With the migration API, theoretically, all messages and message information should be transferred over.

For businesses who decide they must migrate from Slack to Teams, instead of choosing interoperability between the two apps, this is the most likely option of keeping your Slack users happy.

Cons:

A game-changer for most businesses is that messages can only be imported into public channels. If you plan to use private channels, Microsoft doesn’t offer support for this.

One further restriction is the lack of support for backups.

As documented by Tony Redmond, Principal at Redmond & Associates and Author of the Office 365 for IT Pros Book, this process doesn’t include a backup.

“The lack of a backup and restore API for Teams that covers team structure and content is regrettable. Because Teams is interconnected with the rest of the Microsoft 365 ecosystem, it is a difficult application to backup. But that’s no reason for Microsoft to ignore the need.”

Tom Morgan also pointed out that the whole process made his head hurt.

“It’s a ‘behind the curtain’ operation that changes how I think about Teams messages. These aren’t operations for the everyday, but if you need to migrate over messages from third-party systems into Microsoft Teams, these API calls will give you the power you need to achieve it. Just, make sure you don’t break any other parts of the delicate balance of time and space whilst you’re at it.”

You may also like: The Ultimate Guide to Microsoft Teams Message Interoperability