Title:
The title isn't very unique or eye-catching but it does, in the end, relate to the story which is good since an irrevelant title is no good. There's really not much to say about the title besides what was already said. Overall, the title is decent, not the best but it's not terrible.

Description/Foreword:
The description explains the story in two sentences really. You can put together the fact that Baekhyun will have her phone and something embarrassing will happen.

Since the story is quite short and the description explains all of it, really, I don't think there's much point. You really only need to read the description to get the whole story. I mean, I'm saying this after reading though so I'm sure someone who hasn't read it may wonder what's on her phone and whatever else there is.

Plot:
First thing first, I don't think that beginning part with the "statistics" (word count, date started and ending [though, you don't need that. AFF tells you when it starts/ends], etc), per say, is necessary. If anything, that'd be placed in the forward, not the story section. 

As for the plot, there's not really much of a plot considering A) how short it is and B) there's not a real conflict here. There's nothing to 'resolve' to close the story off, it just kind of ends. The ending is pretty open-ended, which isn't always bad but can be frustrating for hardcore readers, and you can kind of imagine what happens after the fanfiction ends so that's A-okay. But there's still not much plot here.

I mean, it could be seen as cliché because there are probably a good amount of these types of fanfics, especially in the EXO fandom, where one member teases a girl and so on, so forth. So, in that aspect, I'd have to say the idea isn't very unique. There's nothing that really stands out about it, is what I'm trying to say.

Writing Style/Flow:
There wasn't much wrong with the writing, I didn't see any grammatical issues or errors so I think you're all set on this aspect. If I missed anything, shame on me haha.

As for flow, well... it's pretty short so there's nothing I can really say about it. If this was a longer story, maybe I'd have more to say but as it's just a oneshot, commenting on the flow is almost... impossible if it's short like this.

Characterization:
This section is the hardest to make any comments on because the characters aren't really presented. And since it's short, it's hard to really understand what their personalities are. I just imagine Baekhyun like the real one and the girl as some shy girl who... works there I guess. There really isn't much to say here as I said before. There's not much real characterization shown here considering the length of the oneshot.

Personal Enjoyment:
I usually do very long reviews but since this was so short, it was hard to really do that since there's not much to comment on, so sorry about that. There just wasn't much to write here.

As for personal enjoyment, I don't really like OC fanfics so, not my cup of tea, and it's too short to get a real plot out of (I like longer stories, chaptered or not). I'm more into horror and stuff like that as well, not really this. Plus, I don't really read EXO fanfics (minus the ones requested and some Sekai ones) so, overall, not for me. 

Again, sorry for the shorter review and I hope you have a good day. Don't forget to credit the shop and if you have any questions, let me know.