"The HomePod has an iPhone processor and pairs with your iPhone--yet it can't make a phone call? To use it as a speakerphone, you need to start the call on your iPhone then select the HomePod as an audio source. You can, however, send text messages from the HomePod with just your voice."
This is the same way with the Google Home. My sister got it for mom for Christmas, and we still can't figure out how she can load her contacts into it, so she can call someone by saying, "Call Trent." The only way to make a call thru it is by voicing the number for it to dial. That means you have to memorize everyone's phone number, or keep a list of numbers close by. Not good.
The first brand to make phone calls thru their device much easier, as well as integrating it more into home features ( microwave, coffee maker, outlets, lights, tv, garage door opener, heating and a/c, etc.... ) they we most successful selling their product.