Doorbird is great except for indoor mounted stations; there are none.

I've worked with one of them. I mounted an iPad on the wall in the kitchen for responding to it, but the iPad's sound output was too low to be practical. I had to use a dry contact that's part of the Doorbird to ring a plain old doorbell. (On the way to finding a doorbell, I see Lowe's and Home Despot no longer have displays of doorbells that let you hear them.)

However, the phone part works nice. I'm in LA... I rang the Doorbird once, and a moment later the client's PA drove up, on the phone, and said "someone in Chicago called to say you're at the front door...."

You're not limited to the multi-phone setup in the info that comes with the Doorbird. A person can manage the phones.

If you call Doorbird for information, say hello to Helmut for me.