Unified Communications

The History And Future Of Message Interoperability

Learn about interoperability's roots, app evolution, multivendor acceptance, and vendors' drive for improved interoperability, and its future in collaboration.
Dominic Kent
Dominic Kent is a content marketer specializing in unified communications and contact centers.

Message interoperability, often shortened to message interop or chat interop, has been a longing desire for enterprises since the general acceptance of instant messaging in businesses.

While today sees enterprises juggle multiple collaboration applications like Microsoft Teams, Slack, Webex, and Zoom, interoperability has been an unrealized need since we tried to manage the sales team using Salesforce Chatter while the rest of the organization was being pushed to use Microsoft Lync.

Even before this, IT managers had their hands full deploying Microsoft OCS and Cisco Jabber on-premises for the first time. When one team procured a new solution, the expectation was that it would be the only solution for that job.

The striking reality is that it has always been this way in enterprise communications. And while some organizations put in blockers and guidance to avoid multiple messaging platforms, personal preference, intercompany collaboration, and innovation have seen shadow IT continue to increase.

Fast forward to 2023 and the same problem is occurring as there are more collaboration apps available for freemium and trial use — often without approval from IT or procurement.

In this post, we look at the origins of interoperability in enterprise communications to understand the future state.


  1. The first instances of interoperability in business communications
  2. Attempts to mediate the multiple messaging apps issue
  3. The evolution of collaboration apps and business reliance
  4. Industry-wide acceptance of multivendor environments
  5. How vendors are playing together nicely
  6. The future of message interoperability

1 – The first instances of interoperability in business communications

Over 20 years ago, Jonathan Rosenberg, CTO and Head of AI at Five9 (previously held senior roles at Lucent Technologies, Cisco, and Microsoft) published the first core document for SIP, RFC 2543. As SIP technology became recognized as a communications protocol, Jonathan was to have no idea of the significance of his work on future communications.

“In the beginning, you couldn’t have products without interoperability. One vendor made the phone, another made the software, and a third would buy those and sell the service behind them. For that ecosystem to work, you needed standards for every feature and function.
Over time, we started to see that diminish. Without standards, you can have greater innovation as you don’t need to go to a standards body to agree on a new feature. The ecosystem shifted and now the client and the server are defined by the same people.
Interoperability is an enabler of ecosystems and how important it is depends on the market landscape. If you look at telecommunications as a whole, it’s been foundational. We wouldn’t have the phone network or the internet if it wasn’t for interoperability.”

This, of course, is the most basic level of communications interoperability. And a long way from what is available today.

From needing interoperability for products to function, we fast forward to today’s world where interoperability is merely a desirable. No case is as obvious as video interoperability.

History of video interoperability

Thinking specifically about video interoperability, we asked David Danto, Director of UC Strategy and Research at Poly, to comment on the first instances of video interoperability he could recall.

After replying with “Wow—that’s an interesting question”, David has authored this section. It makes for bleak reading.

The first commercial video conferencing devices (Picture-Tel, Vtel, a few others) operated over ISDN lines. The standard was called H.320 and was created by the ITU-T around 1990. These systems used a “least common denominator” method, so H.320 calls across brands “worked” but calls within one brand were superior.

(More details on the method can be read on Wikipedia.)

Of course, getting the ISDN lines installed and bonded was a challenge in and of itself.  You needed a device called an NTU to do that, and one could only install it after the installation of phone lines.

When the ITU-T came out with H.323—video over IP—it was a whole bunch easier.  Then around 2006 we had to live through the “Immersive TelePresence” fad that lasted six or so years, then faded as it should have.

Now every platform uses its own proprietary codecs—all claiming to be using “the correct version” of WebRTC even though they are all different versions of multiple codecs like H.264 / HEVC video.

So we’re as far away from universal interoperability as we ever were.  

Most services have the ability for an older SIP/H.323 system to join it. And there are various interop features in each platform (‘join a platform “M” call from a platform “W” system, etc.’).

There are also third-party services that promise to remove the interoperability complexity for users.

When the pandemic ends and we all head back to offices with their new purpose (collaboration, camaraderie, brainstorming, etc.), the interoperability problem will again become critical as not all room systems are certified with all platforms, and many of the platforms are actively against systems allowing for easy switching between services.  

Also, platforms are expanding the use of multiple-stream calls—allowing participants to see more than one video participant simultaneously—which will also add difficulty to allowing interoperability across platforms.

The history of message interoperability

The history of message interoperability has played out in a similar fashion.

The first instance of message interoperability is often noted as federated XMPP.

Federated XMPP

Federated XMPP is defined as an open standard in an application layer.

XMPP itself is an open standards-based protocol like that of email. As it is “open” technology, there is no single owner of the XMPP network.

The term federation signifies a boundaryless system—like independence in the government use of the word. For instance, you can send a message to someone on another platform without hitting a wall.

It used to be the case that RFPs often had requirements for solutions to support open standards like SIP and XMPP, says Tom Arbuthnot, Microsoft MVP and Founder of Empowering Cloud.

“Especially in government procurements, these were ”must-have” requirements, even when few vendors could really deliver them. Over time these requirements have dropped away.”

In March 2019, a post on the Y Combinator chat board suggested “Plenty of us are still working on XMPP, and there are thousands of XMPP servers and many more users on the network.”

In fact, Zoom uses XMPP to this day. To send messages between users of its persistent chat feature, Zoom Team Chat uses XMPP with some proprietary extensions.

2 billionWhatsApp
300 millionZoom
45 millionCisco Jabber

On the use of XMPP, David Strom, a freelance IT writer covering business communications, has written:

“The protocol came too little, too early. Plus, the proprietary walled gardens of AOL, IM, and SMS made it almost impossible for XMPP to make any headway.”

Since the advent of more and more feature-rich messaging platforms, personal preference, and departmental use cases have reigned supreme.


Trillian was introduced as a way to bring personal messenger apps into one place. Unlike native interoperability, which would mean you don’t need a third-party app (and interface), Trillian’s aim was to provide a unified inbox.

This meant chats from AOL and Yahoo! Messenger would come into a centralized inbox.

Today, Trillian is its own messenger platform. You can extend to open platforms like Olark and Jabber but as apps move to enhanced versions (i.e. Google Talk to Google Hangouts then Google Chat), support and feature parity is disappearing.

While Trillian was not interoperable in the genuine sense, the goal of the app was to allow users to talk to many systems at once.


Adium, which supported AOL IM, Twitter, and Google Talk and now has some basic support for WhatsApp and Telegram, continues to bring open messaging platforms together.

If you use macOS then you can still bring chats from XMPP-based apps into a unified inbox.

Again, this is much-needed functionality but restricted by only being available to macOS users. If your business has users on Windows or Linux, there is no way to connect with them—defeating the point of interoperability.

Back in the business world, there has been little history of genuine message interoperability.

Upon recognizing this administrative and communicative problem, IT managers and admins have been faced with several challenges when attempting to mitigate risk and “solve” the issue of multiple messaging apps.

2 – Attempts to mediate the multiple messaging apps issue

When attempting to remedy the “problem” of multiple messaging apps, telecom vendors have historically leaned towards displacing the competition rather than interoperating.

During the 2010s, unified comms (UC) vendors went to market as a single platform play. There are, of course, considerable benefits of having a single platform for collaboration. The strength of this play was only increased if the UC vendor also sold contact center.

The appeal of a single vendor for both unified comms and contact center was often strong enough to win new business without diving into functionality and pricing. Especially as we moved into the as-a-Service era and cloud technology made bringing new features to market quicker than ever.

While seemingly ideal, this created a unique problem for IT managers. Migration, adoption, and maintenance of a new platform involves resources, expertise, and cost.

Shadow IT in business messaging

The harsh reality for IT teams forcing users to move to new software? Users liked the old option. Or they, at least, had got so used to it that it had become an autonomous action.

This period of change is the biggest creator of shadow IT. When people have access to another app—their personal preference—they are going to use it.

How did IT teams combat this problem? Well, just turn the shadow apps off, right?

Attempts to block Slack fell on deaf ears. As you may well have guessed.

When potential blocks and unapproved apps lists have failed, the temptation has been to find a new app to bring all these apps together.

Apps like Sameroom and NextPlane did a good job of combining messages into a holding pen for business messages.


Sameroom was cleverly named as you could literally bring your messages into the same chat room.

Icon of Slack to the left connected by a pink spring to the icon of Skype to the right.

Acquired by 8×8 in 2017, Sameroom is now used to connect 8×8’s apps with other messaging apps through its tube technology.

Founder and former CEO, Andrei Soroker, said Sameroom gained momentum because “People kept asking us to connect Slack to something else during the messaging explosion of 2014.”

8×8 users can now create tubes between 8×8 Virtual Office chats and their Slack counterparts, for example.

The exhaustive list of available tube integrations includes:

  • Skype
  • GroupMe
  • Telegram
  • Slack
  • HipChat
  • Yammer
  • Salesforce Chatter
  • Webex
  • Gitter
  • Mattermost
  • Fleep
  • Rocket Chat
  • Planio
  • Flowdock

Andrei says that Sameroom became limited as Slack dominated the messaging landscape and messaging apps, in general, were “aggressively non-interoperable”.

Which was the goal. Andrei says Sameroom “explicitly wasn’t building Trillian for Business” and that a major use case was how agencies need to chat to customers who use other apps.

Agencies often have a static number of partners and need to keep a team communication dynamic.

Andrei says that more locking down and vendor power continued. When Microsoft Teams started to dominate the market, the Microsoft bot network was not as accessible as it had been with Skype.

Add to that major apps like HipChat and Atlassian Stride being made end of life, and it’s easy to see how message interoperability progress has stalled.

Andrei says, “There needs to be successful legislation for interop to succeed.” The American Innovation And Choice Online Act may provide just that.


Another player in the early message interop market was NextPlane. This technology provided cross-platform capabilities for apps like Jabber and Skype for Business.

Achieving close to native message interoperability, NextPlane provided the ability to send plain text messages, emojis, and GIFs from one platform to another. You could install a bot to impersonate a user on the corresponding platform.

While this solves the basic problem of cross-platform messaging, the addition of an app and a link to start the channel creation causes a change to the Teams user’s routine.

When a new channel gets created in Teams, for example, a user has to click a link from the Nextplane app to join the channel and start chatting with Slack users.

A Teams user hovering the cursor over a link sent from Nextplane.

The ideal scenario here is:

  • Channels get created on Microsoft Teams and Slack
  • Users get added
  • Members of both Teams and Slack chat cross-platform

When rolling out channels between platforms at scale, even small elements like this have been blockers to adoption.

3 – The evolution of collaboration apps and business reliance

Since Slack arguably pioneered asynchronous messaging in 2013, persistent chat and a new era of “team collaboration” have skyrocketed. No longer is messaging instant-only. We can send messages and people can reply to them tomorrow without the history disappearing.

We use channels, teams, message threads, and notifications to function more productively than with IM and calling only.

The Slack interface with a channel named, "marketing," clicked.
Example of new features in team collaboration apps like Slack

But with the success of the category comes new challenges IT teams weren’t prepared for.

In an interview with Mio in 2018, Ryan Purvis, CTO of HiLo Maritime Risk Management unveiled how he deals with notification overload.

“I turn off all my notifications on all my devices. I try batching my communications and limiting my messaging.”

The improvements in technology are doing more good than bad. Think of the things you can do in Webex or Microsoft Teams today compared to Jabber or Skype a decade ago. We can now work asynchronously as standard and build workflows and task management into our communications apps.

Tim Banting, Practice Leader at Omdia, says that a more distributed workforce is driving greater demand for asynchronous ways of working.

“Businesses will begin to focus less on work locations, and more on ensuring they have the right infrastructure, tools, and practices in place to help employees work productively from anywhere.
The global and distributed nature of work, combined with a complex digital supply chain (partners, suppliers, temporary staff etc.) makes it increasingly difficult to work both synchronously (via voice, video, and meetings) and within the same application. So, messaging between disparate services without having to switch clients or manage different accounts will become increasingly important.”

With no physical HQ, Slack, Zoom, and the likes are core infrastructure. If they go down, it’s the equivalent of a power outage in the office.

It’s the use of they that is particularly interesting in the case of message interoperability.

91% of businesses report they use at least two messaging apps. This means apps like Slack, Zoom Team Chat, Webex, and Microsoft Teams are co-existing in multi-vendor environments (without interoperability) and it’s just the norm.

4 – Industry-wide acceptance of multivendor environments

Chiradeep BasuMallick, a technical writer for ToolBox, writes that there is a chronic lack of cross-platform visibility that is counter-intuitive to the user experience.

Despite this, 3.3 is the average number of workplace chat apps in use. And 14 is the number reported in a recent Frost and Sullivan survey as the “best collaboration app.”

From these findings, it’s safe to conclude that while Microsoft Teams is the clear leader in daily active users (145m+), it’s rare that Teams is the only app in use.

With a lack of interoperability options, IT professionals managing these environments have had few alternatives to accepting multi-vendor environments.

With this acceptance, IT admins must prepare for support even when apps are deemed as shadow IT. Failure to acknowledge that apps outside of the corporate stack leads to unhappy employees, reduced productivity, and unresolved tickets.

Chad Reese, Senior Director of Technology at Pro Football Hall of Fame, comments on how acceptance and preparation help deal with mixed technology stacks:

“When you don’t know these things are happening, it can cause a lot of pain down the road. So, with messaging, it’s important we cater to our employees’ needs. Sometimes our users are ahead of the business technology at the time.”

By 2023, it’s no longer just the people responsible for implementation and support who are acknowledging multiple apps do and will continue to exist.

“I’m a big believer in allowing choice in the marketplace. Interoperability tools like Mio are enablers of customer choice.”
Jonathan Rosenberg, CTO and Head of AI at Five9.

Jonathan has been vocal about the need for interoperability for decades. But now vendors are doing something about it.

We’re witnessing what could be a changing of the guard when it comes to single vendor lock-in versus interoperable solutions.

5 – How vendors are playing together nicely

If we’re acknowledging that multi-vendor environments are the norm, it’s a sensible assumption that those vendors recognize the need for interoperability. As end customers need to use several platforms at one time, where is the benefit of holding back the user experience?

Thankfully, the majority of vendors have started to play nicely. Platforms like Microsoft Teams, Slack, Webex, and Zoom have made their APIs accessible to partners like Mio to enable cross-platform chat.

Furthermore, the number of integrations per platform is growing every day.

You can see a list of integrations per platform in these posts:

Webex is now rather publicly an open and interoperable application. And it’s not only the tech that makes this happen. In an interview with Mio, Abhay Kulkarni, GM and VP of Webex App, said:

“From a competition perspective, if you make the end user’s life easier, competition takes care of itself.”

The openness from leadership and market positioning goes further than Webex too. Patrick Kelly’s role at Zoom is officially “Distinguished Architect” but he spends the majority of his time working on producing content and assisting sales deals when Microsoft Teams clients need to integrate with Zoom.

A side-by-side view of Zoom's interface and Teams' interface.

Rather than displacing Teams with Zoom, the approach is to interoperate. On the Mio podcast, Patrick mentions a huge part of his role is educating customers how Zoom and Microsoft Teams can work together.

Both Cisco and Zoom showed considerable interop buy-in when investing $8.7m in Mio in late 2021.

This is backed up by Jeetu Patel, EVP & GM of Security and Collaboration at Cisco:

“Cisco has a decades-long commitment to delivering openness and interoperability for our customers, and we are delighted to support Mio’s efforts to advance cross-platform messaging across the Webex ecosystem.”

Microsoft has also publicly stated its recognition to be interoperable. In 2021, Jeff Teper, Head of Microsoft 365 collaboration, told The Verge this on the announcement of Teams interoperability with Workplace from Facebook:

“There’s not going to be a one and only communications tool on the planet. People are going to choose a number of tools, so it’s on us as responsible vendors to make sure they can interoperate.”

Slack CEO, Stewart Butterfield, has mentioned the “great value of interoperability” in an interview with The Verge:

“The siloing and fragmentation of knowledge into these different systems, while it’s still definitely a huge net plus to use them, is a real challenge for organizations. And if you have this central medium, you have this lightweight fabric for systems integration. It’s disproportionately valuable.”

So, with vendors coming around to interoperability, what does the future hold for those that matter—the people using and administering these apps?

6The future of message interoperability

In personal messenger apps, the future looks more like the unified inbox approach as Beeper gains more and more traction.

Beeper takes the concept of Trillian and allows you to have a single inbox where your messages from the following platforms are received and responded to:

  • Android (SMS)
  • Whatsapp
  • Twitter
  • Facebook Messenger
  • Slack
  • Discord
  • Telegram
  • Hangouts
  • LinkedIn
  • Signal
  • IRC
  • Instagram
  • Matrix
  • The Beeper Network
  • iMessage

In business messaging, the need is more complex and the future of interop is more compelling. We can split the types of needed message interop into two categories:

  1. Internal message interoperability
  2. Federation for intercompany collaboration

Internal message interoperability

When an organization has two or more messaging apps in place, there must be a method to connect the two sets of users together. Otherwise, workplace silos form and there is a disconnect between teams.

For example, when a business has both Google Chat and Slack users, it is often the case that a pocket of Slack users exists in marketing and development teams.

This could represent 500 users who work productively and accelerate their marketing campaigns using Slack and Slack alone. But what happens when they need to collaborate with sales teams and billing colleagues who all use Google Chat?

Without interoperability, they would revert to email or set up real-time meetings for even the smallest items. While there’s no tangible issue using these methods, it doesn’t make sense to disregard the technology available.

When businesses embrace message interoperability, they can connect users and channels on both platforms and send messages from their preferred app.

All that’s required is the technology to enable this, and the time to configure which channels and users need cross-platform access.

Mio CEO, Tom Hadfield, comments on the uptake of business messaging and how Mio aims to nip platform fragmentation in the bud before it gets out of hand.

“Everything I’ve seen so far suggests that one day the number of chat conversations between users on the same platform (eg, Slack <> Slack) will be dwarfed by those between users on different platforms (eg, Google Chat <> Teams). At Mio, we’re building infrastructure that will ultimately need to process billions of messages per day between Google Chat, Teams, and Slack users.”

There will be pushback from platform champions. Slack fans will always prefer Slack. But interoperability doesn’t mean those users who live in Slack have to do anything different.

Once you sync platforms, there’s little difference messaging a Slack user than messaging a Google Chat user.

What’s next for message interoperability in intracompany scenarios?

There are three key elements that will make message interoperability the norm in the future:

  1. Presence sync
  2. Onboarding new platforms
  3. Early adoption
1 – Presence sync

If we’re going to be messaging users cross-platform, it’s only natural to want to know if they’re online. This means you can anticipate a reply if the person you messaged is online or knows to move onto a new task if they’re offline. Presence sync is on the Mio roadmap.

2 – Onboarding new platforms

Message interoperability can’t be limited to certain platforms. That’s not interop; just choice. It will take a group effort from the leading platforms to come around to the idea of message interoperability. And if the lead of other major vendors is anything to go by, it may not be that far away.

3 – Early adoption

Early adoption is crucial when introducing message interoperability. Trying to engineer a workaround or fix is harder than setting up your organization to use Google Chat and Slack together from day one.

As the scenario for interoperability from the beginning is unlikely, it must be a simple process for IT admins to put in place. Innovations like the Mio Hub enable admins to sync channels and users, enable settings, and review activity.


Collaboration interoperability has been thought of as taboo by vendors for a long long time.

We’re potentially going full circle in telecoms from open SIP and XMPP to walled gardens and back to native interoperability enabled by APIs and middleware.

To get to this point, there have been hurdles, and there will continue to be.

As new features roll out on one platform, they may not be supported on another. New platforms may come to the fore. And most importantly, interoperability needs to be considered during the initial collaboration rollout.

Reactive interoperability works. Planned interoperability can truly change businesses.

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