Hi @Nathan Smith
Some users always test the link with "CALLTO://xxx" when using classic Teams and encounter the same problem as you. However, when using the new Teams, he excludes "//" and the link will work. Therefore, it is recommended that you try typing "CALLTO:xxx" to see if it will work as expected.
If this does not work, please send feedback at Microsoft Feedback and vote on issues similar to yours. Many features of our current products are designed and upgraded based on customers’ feedback. With requirements like this increase, the problem may well be released in the future.
Thanks for your understanding and support.
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