It's a small thing, but my house sometimes calls me.
Our apartment block uses the type of intercom that you can answer and speak to people on, as well as buzz them into the building, but it only works over a phone line with a local area code . Not having a landline, it's inconvenient for us to have the intercom only connect to one of our personal phones to let people into the building, and my cell phone has an area code for an entirely different state anyway, so we needed a way to have the intercom ping either of us at any time.
To get around the issue, we use a shared Google Voice number. Google Voice lets you pretty much pick your phone number, so it's trivial to get a local area code. You can then forward calls to the new number to multiple other phones, or pick up the calls via the browser. It's a surprisingly seamless fix.
I could have not added this number to my contacts - but giving the number a name denoting who it belongs to (it's Wodehouse's number) and a way to talk to us is part of the theory I have around making the house seem smarter.
I don't say there's "someone at the door" anymore, I say "Wodehouse is telling me someone is here".