This compelled Business Insider to conduct an investigation, the results of which turned out to be quite simple!
The investigation was performed in three steps –
1. With contacts saved on the phone
2. With unknown numbers (non-iPhone as well)
3. When the phone is locked or unlocked
As per the results, it doesn’t matter if you’re receiving a call from an iPhone number or any other OS number. It doesn’t matter whether the contact is saved on your phone or not. The only thing that makes a difference is whether the screen is locked or unlocked. When the screen is locked, your iPhone will give you the option to “slide to answer”, whereas when it is unlocked it will give you the option to “accept” or “decline” the call. So this is the simple answer to a question that baffled many!