DECT phone system where, when using the intercom

[Ronny]

I can broadcast to all phones, without the receiver's intervention?
Almost like an intercom desk telephone at a business?

I would like to broadcast throughout the house voice messages, like "dinner is ready"

I can't find any...

[N7AS]

Get some Amazon Echo Dots. They are cheap and you can announce to all of them at once.

[Ronny]

I received a few new Panasonic's that did the trick.  Wow, so convenient, and so much  faster than Alexa, and it's a phone too!

Regards