Microsoft Teams Coexistence Mode Changes & Caching Delay

Matt Ellis
May 8 · 6 min read
Coexistence Modes (Image from here)

What are coexistence modes?

For anyone looking for more info about the various coexistence modes these three pages on docs.microsoft.com will give you most of the info you need to know:

The Change

A quick look at the usage reports via the O365 Admin Portal showed that we had a few very keen early adopters of Teams who were using private calls, private chats and Teams meetings a fair bit. So, to avoid forcing them back to using only Skype it was decided to keep a number of people on Islands mode until we could move them to TeamsOnly mode. They were already successfully working with both platforms so this wasn’t too much of an issue.

  1. Change the organisational default coexistence mode to SfBWithTeamsCollab

Wait, then wait some more…

It turns out there is a fair bit of caching involved in switching people’s coexistence mode. As a general rule, 24 hours should be enough time for this to all sort itself out but in certain circumstances this could take longer.

Change Timeline

This was the timeline to my change. Your mileage may vary:

  • ~18 hours: Messages still being sent to Teams despite SfB coexistence mode. Fresh download of client cache made no difference. Suspect service cache not updated yet.
  • ~22-24 hours: Correct coexistence mode starting to show for some users in web client and other machines. Would show in desktop client if fresh client cache download was forced.
  • ~36 hours: Changes confirmed on non-forced client.

Lessons Learned

If you can, build in a good 24 hours to allow things to settle down after making coexistence mode changes to a lot of users. In fact, if I had to do it again, I’d probably do it over a weekend to be safe.

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Matt Ellis

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Unified Communications Architect, Pompey fan, burger eater, coffee drinker...

365 UC

365 UC

Stories from the world of UC by a bunch of UC professionals…