The game is very impactful. It starts with the simple idea, but on the way it transforms into something deep and struggling. Personally, I have an experience as a dispatch caller, I was doing it for couple of months and it's very taunting. You learn a lot of things by helping people and I got that personal attachment to the game.
Although, the ending was a bit off, I would say the aim for this is psychological, rather then monster and scary thing grabbing you, but I don't know, maybe the idea is very different for you as a developer.
I just felt the ending needed a more visceral connection.
This is just an idea, which you can freely use or don't, your choice - I think the ending call was supposed to cut out and then, instead of the monster, we as a player could have been transported, like in a scene, to that location, where we would realize, it was us, who saved/or did not save the girl. Maybe, that way, the fire behind the door, which we see towards the end, would actually make sense.
Overall, I loved the game, it had the perception and real visual connection to the story and yeah, besides the ending, everything was fantastic. Looking forward to seeing more games from you. Good Luck.