But other times you may see a screen with a slider that says slide to answer with no option to decline.

So what's going on here?

Well, Apple actually provides two different incoming call screens depending on the state of the device.

If it's unlocked and being used, it'll show the red and green buttons.

If it's locked, the slider appears instead.

The reason Apple does this is to prevent users from accidentally answering or declining calls while their phone is in their pocket, bag or purse.

The buttons are easier to press, so Apple only shows them if you're actively using the phone.

While the slider is much harder to activate accidentally.

But this wasn't always the case.

The first five versions of iOS only had one incoming call screen with the red and green buttons.

But users complained that they would accidentally decline or answer when reaching for their iPhone to see who was calling.

So in iOS 6, Apple introduced the slide to answer feature when iPhone was locked.

But it wasn't really a new concept though.

Apple would use slide to unlock since the original iPhone to prevent users from accidentally unlocking their device and dialing numbers.

This was actually a common issue with mobile phones at the time, and it was called butt dialing.

Almost anyone who had a cell phone experienced this.

In fact, when iPhone was introduced, many people assumed butt dialing would become more common since the screen was activated by touch.

But because Apple used the slide to unlock feature, it became less of an issue.

In today, butt dialing hardly ever happens.

Which is why it was a no-brainer to use the same feature for the incoming call screen, making it almost impossible for users to accidentally answer or decline calls.

In fact, Apple may have made it too difficult.

Because many users don't even know how to decline a call when the slide to answer screen appears, since there's no visual cue.

But it can be done by double pressing the side button.

So that is why iPhone has two ways to answer calls.

This is Greg with Apple explained, thanks for watching till the end and I'll see you in the next video.