cellphone cameras have small crappy lenses, so they are really weak with light, so you should try altering that
a night shot will get really blurred, because the lens is small, so it will nead a higher shutter speed (like 1 sec).. general photos get kind of blurred or out of focus, so you could alto try playing with that, and because light conditions are weak within these cameras, you generally don’t get fine colors or contrast
then most of these cameras will have some post-processing applied to try to correct lens’ faults and porr quality, so this post-processing will most likely add gain/brightness, contrast and maybe some saturation to try to vivify the photos…
if i were you i would try to push down the photo to what i think the camera would capture (dark, blurred, poor-colors), apply the noise and stuff (because the camera will capture that), and on top of this, give the contrast, the saturation, the light gain, etc.. doing this will help to mimic what happens inside a cellphone camera, as some color values will get altered, and this way you will also get the post-processing applied over the noise.
note that before the post, the noise should not look like cell-camera noise. it should be a more raw noise, only after the constrasting and saturating will it look like cell-camera-noise..
i’m actually not quite sure what those cameras do about post-processing, but you can also try to investigate that out.