Microsoft's Kaizala messaging service for large-group communication is on its way to becoming part of Microsoft's Teams group-chat product. Kaizala is phone-number based and includes mobile app versions for iPhone and Android phones. It fits into Microsoft's strategy to try to get more firstline workers to use its products and services.
(I asked if Microsoft also plans to continue to make Kaizala available as a standalone/separate offering for those who don't want it as part of Teams. No word on that so far, though this simply may end up being a licensing discussion.)
In the time period leading up to Teams integration, Kaizala is getting some new features. These include @mentions for tagging individuals in a conversation; the ability to delete a message in a one-on-one or group chat within an hour of sending it (or at any point in time if the user is a group admin); and a new Kaizala web app, available now in preview and targeted to be generally available to all Kaizala users later this quarter. Microsoft also is adding image annotation and video calling to the product.