Hi @Alain Reid ,
This feature seems not rolled out for IOS device yet. Only a few android devices compatible along with a jabber headset. For more details about it:
https://learn.microsoft.com/en-us/microsoftteams/walkie-talkie#walkie-talkie-devices
We also recommend you give your feedback in Teams UserVoice (https://microsoftteams.uservoice.com/forums/555103-public). Microsoft will always focus on customer’s feedback and experience. Some new features would be added to the services based on customers' feedback in the future, and your good ideas will be very helpful for them to improve the service.
Your time, understanding and cooperation will be highly appreciated.
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