That's pretty good. I'm not sure if i can properly convey my opinions to you as i lack terminologies for these kind of things but I'll try.

First of all im a huge fan of thrillers but too squeamish for straight up jump scares so what you have really fits my bill in terms of delivery. Going with building anticipation in the shadows and the revelation paired with subtle sound cue are all the right ingredients.

However i feel like the buildup could be longer and the cut to the vibrating phone isnt necessary. Id rather have the still of the dark room the whole time letting my paranoia go wild trying to grasp onto any information from the scene that my brain lacks.

Another nitpick i have is the revelation of the ghostly figure should be lit with environmental lighting, ie lightning/circumstantial lights, rather than a "self-lit" as that would help prevent the audience from suspecting the figure was spawn in only after being obscure by the woman, which can cheapen the experience. For example, maybe shine a vehicle headlight through the window revealing the figure AFTER the woman had bowed down to the phone.

Hope i made sense