Slack + Microsoft Teams + Webex News

7 Ways to Connect Microsoft Teams and Slack in 2021

Connect Microsoft Teams and Slack


7 Ways to Connect Microsoft Teams and Slack in 2021

Connect Slack and Microsoft Teams

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 7 ways to connect Slack and Microsoft Teams then gone out and found a better one for internal use and a better one for external use.

1 – Connect Slack and Microsoft Teams without introducing a new chat client

Native federation


There are services in the marketplace that allow you to federate with other enterprises via their own chat client, but this doesn’t resolve the issue of multiple chat platforms in a single organization.

It does, however, bring them together in a slightly improved chat client.

Natively, apps like Skype for Business also provide this functionality. Skype for Business users just need to turn on the federation facility within their Office 365 admin portal.


Some UC providers have started to introduce cross-platform messaging into their collaboration offerings.

Whilst this does remedy the issue of switching between multiple apps, the solution here is to totally replace the solution you are already invested in.

You can message any number of other businesses using most chat apps. But, this comes with the disadvantage of giving up the native app that everybody uses.

Guest access


Take the typical example where your engineering team loves Slack and your IT and Sales teams prefer Teams.

Guest access on both platforms allows external parties to join in the conversation, but access is limited.

Microsoft Teams guest access


Removing either (or both) of Slack and Microsoft Teams, in favor of a catch-all UC solution, almost always results in using Slack and Teams for some services.

Obviously, this is the ideal scenario for the UC provider. However, they may not always be the best fit for the business.

Moving your messaging stack to a new product could still leave you heavily invested in Microsoft Office 365 – a waste of a powerful app already paid for in your Office 365 strategy.

All in one solutions often mean yet another user interfaces for your teams so get used to

2 – Configure webhooks for Slack & Microsoft Teams


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.

Typical example of a webhook


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.

Setting up a webhook for Slack

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.

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


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.

Slack Microsoft connector


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.

Channel Surf can act as a workaround for connecting Slack and Microsoft Teams but is limited by Microsoft's API

4 – Create your own app using an app builder


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.

Typical apps available with app builders include Slack and Microsoft Teams


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.

You may like: 9 stories from a year talking to Slack, Webex, & Microsoft Teams customers

5 – 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, April 2020. 


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. 

Slack and Microsoft Teams calling integration

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. 


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 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, our CEO Tom Hadfield commented on 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.”

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 to 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:

Slack to Teams migration API


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.


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 every day, 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.”

7 – Federation to connect to external guests across Slack and Teams

Do you communicate with people outside your organization as well?

According to research, they’ll likely be using Slack or Microsoft Teams, but not necessarily the same as you.

It’s hard to chat with freelancers, contractors, and suppliers when you’re not on the same platform.

When this is the case, it becomes extremely unproductive moving out of your app to accommodate your guest.

Or even worse, end up resorting to email like it’s the 90s. (Okay, email has a purpose but you get the point).

That’s why Mio has created universal channels for Microsoft Teams with Slack.

You can stay in Teams and send messages to your contractors, suppliers, or clients that use Slack.

Stay in Microsoft Teams and chat with Slack users and Webex Teams users

They stay in their platform too and Mio translates the messages across platform.

And it’s not just messages that are supported! GIFs, emojis, channels, DMs, and message edits/deletes are all supported.

Stay in Slack and chat with Microsoft Teams and Webex Teams users

If this sounds like something you need, try your first universal channel for free here. Your first three are completely free.

Try it for free
Leave a comment