Silverlining. It shouldn't close down at far as making calls or sending texts but it's going to struggle finding storage space.
The storage is Gigabytes Gb (nine zeros) not Megabytes Mb (six zeros). Difference between billions and millions. In other words, you have 200 Megabytes left.
Go into Settings, General, iPhone Storage to see how the 15.8Gb is being used. On the multi-coloured bar graph, you’ll see the two grey areas iOS and System Data. Scroll down to the bottom and you will see how much memory they each take up. There is nothing you can do about iOS which takes about 7Gb. System Data should be around 5Gb. If you are using a lot more than that, it could be that your browser is storing a lot of temporary data that can be deleted. Go back to Settings, Safari and select Clear History and Website data. See how much difference that makes. You might lose a few passwords for different websites but they can always be reset.
With only 16Gb memory and needing say 12Gb for iOS and System Data, that's going to leave 4Gb (four billion bytes) for everything else but that’s still pretty good depending on what else you are using and storing.
Do you know how to capture a screen shot from your phone? Press the on off button top right and the round Home button at the same time. You'll hear a click and the capture will be saved in Photos.
Go into Settings, General, iPhone Storage. See if you can capture the multi-coloured bar at the top and post it here. Make sure there is nothing in the photo which identifies you.
If you don’t want to do that, then can you just scroll through the storage and say what’s taking up the most storage e.g. how much is being used for Photos (or are they stored in iCloud?), how much for Messages, how much in total for apps - a guestimate from the bar graph will do. Is anything else taking up a lot of storage?
Some apps only use relatively few Mb. For example, BBC News is 104Mb, my county library app 21Mb, my energy supplier app 18Mb, my banking app 68Mb and so on but of course, that does all add up.
If you are storing a lot of photos on the phone not in iCloud that will add up too. Chose a photo and tap it. Swipe upwards in the middle of the photo. You should see how much memory it is taking up. It’ll give the focal length and aperture, the camera resolution 12Mp (megapixels), the size of the image x * y and a number of Kb (kilobyte) or Mb. A colour-rich photo could take up 4 or 5Mb.
Hopefully, this is some help to find out how that 15.8 Gb is being used and may help you to free up some more of that.
