From HowToGeek.com….
Siri lets you use your HomePod or HomePod mini to send messages to others in your household, provided they’re within earshot of a smart speaker. This feature is called Intercom, and you can use it from any device that supports Apple’s voice assistant.
Although the Intercom feature is primarily designed for use in the home, it also works with the iPhone, iPad, iPod Touch, Apple Watch, and CarPlay.
