What Is Apple Intercom?
you’re able to even use it with your Apple CarPlay.
How Do I Turn on Intercom on the Home App?

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Your devices need to meet three qualifications to turn on the Intercom app:
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That’s it.
To check it, go to theHomeapp and tap theHomein the upper-left corner of the screen.
Then tapHome configs>Intercom.

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How Do You Use Apple Intercom?
For example, “Hey Siri, intercom dinner is ready, wash up and come eat.”
Siri will announce on all the devices in your home, “Dinner is ready.
Wash up and come eat.”
When you don’t specify a room, your announcement goes to all the connected devices in the household.
Siri will repeat your message, but only in the kitchen (or whatever room you specify).
Using either method, you’ve got the option to reply to intercom messages as well.
Does Intercom Work Without HomePod?
The Apple Intercom function will work without an Apple HomePod, but there’s a catch.