When a call comes in on your iPhone, you may have noticed that you see a different set of options when your phone is locked, compared to the options available when it’s unlocked. While the unlocked options seem more flexible, you still have a bit of flexibility available when your device is locked.
The main difference that’s always bugged me is the lack of a “Decline” button on the locked screen. All you see are the “Slide to Answer” gesture to answer, a “Remind Me” icon, and a “Message” icon.
You can however, reject a call, even if you don’t have the “Decline” button handy. To decline a call from the lock screen, simply double tap the power button on your iPhone. (It’s the button on top of the iPhone for the 5 series devices and older, and it’s on the side for iPhone 6 and 6 Plus.) Double tapping rejects the call and sends the caller to voice mail. A single tap of the power button silences the call ringer without ending the call.
You can also set a reminder or send a text message to the caller from the locked screen. To decline a call, but set a reminder so you don’t forget you received the call, tap the “Remind Me” button. You’ll then be prompted to enter a time to be reminded about the call. Press “Message,” and you can send a text message to the caller.
Thanks to “Rocket Yard Blog” for the original tip.