Really cool concept and use of the theme, also really cool art style.
I feel like the first half of the game (taking calls, increasing connection etc.) in the small room was the strongest part. It felt like one of those great niche horror games that take place in one location (Iron Lung for example) and I really think it could be used to tell a really great story/make a great game.
I felt the second half, after I possessed Franz was a little weaker. Art style-wise and also story-wise, I wasn't really sure if there was a way to avoid the strange creature/spectre.
Overall though I really enjoyed your game! Well done.
There were some minor issues with the text in the UI during conversations also, but it wasn't a huge deal. (Windows download, haven't tested web build).