Three biggest iPhone mysteries revealed – including the flashing red dot

YOUR iPhone has plenty of design quirks that may have made you scratch your head.

There are three commonly spotted mysteries that are easy to explain.

iPhone mystery #1 – frame lines

You may have never noticed them before, but the lines on the back of your iPhone are actually antennas. 

Depending on which model iPhone you have, these lines will be located on different parts of your device.

This piece of engineering is critical for your device's functionality.

It not only connects the phone to its network, but also to WiFi and Bluetooth.

These lines are generally placed on the outside of a phone because internal all-metal construction would prevent the radio waves from escaping.

For this reason, it's important that iPhone users do not cover the antennas up with a metal phone case.

Otherwise, they may find themselves in a situation where it's preventing connectivity. 

Such was the case with the iPhone 4, which suffered many problems with its antennas.

Users were having reception issues when they held their devices "the wrong way".

However, if you have a phone that is not made of metal, then you're unlikely to have antenna problems.

That's because radio waves can penetrate easily through plastic and glass.

iPhone mystery #2 – speaker grille

Apple has been playing a visual trick on you for years.

At first glance, the bottom of your iPhone looks totally normal.

You'll see a Lightning port for charging your phone, possibly an antenna strip, and two speaker grilles.

Only one of your speaker grilles doesn't actually contain a speaker at all.

Yes, the left one is a "fake" – and has been ever since the iPhone 7.

You can even test it out yourself.

Play some music and then cover the right speaker grille with a thumb – and your sound will be silenced.

Try it in reverse with the left grille covered and you'll notice no difference to the sound.

It depends on the specific model, but it's mostly for symmetry so that the iPhone looks better from the outside.

On some models, some of the left speaker grille space is also given over to microphones.

It's a strange bit of fakery on Apple's part, but it's probably for the best.

You'll also have microphones at the top of the iPhone and near the camera on the back.

Before the iPhone 7, Apple simply used a dedicated microphone hole on the bottom-left of the device.

iPhone mystery #3 – red light

If you've ever used an iPhone in the dark, you might have noticed a faint red light.

It appears at the top of the iPhone and is very difficult to see except in the darkest conditions.

If you have seen this before, don't fear that someone is spying on you.

This is actually one of many sensors needed to make Face ID on iPhones functional.

Face ID is a powerful tool and requires a number of sensors, like an infrared illuminator, to work.

When it's low-light conditions, like nighttime, it is normal and common to see it.

In some other cases, it could be Face ID's infrared proximity sensor that you are seeing. 

These sensors capture and analyze more than 50 different facial muscle movements.

They also enable users to use emoji characters such as a panda or a unicorn on FaceTime – as well as some app features.