The iPhone incoming call problem

I can't explain why, but one morning I woke up thinking about the problem of accepting or declining calls that @adamsilverhq discussed in his newsletter.

I've never received a call while on another, but if I did, this UI would confuse me. I'd likely miss the incoming call because it would take too long to decide what to tap, or I might tap the wrong option.

I started thinking about the landline phones I used in previous jobs. They had the usual controls for making and receiving calls, along with multiple lines. You could easily switch between these lines, but the controls remained consistent.

I wondered if this interaction would work on mobile, so I did a quick sketch, and created a prototype using Apple’s design kits.

Interactions

• When a second call comes in, the calls turn to radio cards, like a line.

• The controls don’t change so users don’t have to quickly understand a UI they might not have seen before.

• Users can easily switch between lines.

• The selected call moves to the top for emphasis.

• The “on hold” call moves below to make it easier to select with one hand.

Nuances

• If the user taps "End" on the current call, does the incoming/on-hold call become active immediately?

• What happens to the incoming call if "FaceTime" is selected?

• What happens if "Keypad" is selected?

• How can the user dismiss an incoming call while on another? Swiping left works but isn't intuitive for everyone and may conflict with radio card selection.

Tackling this challenge was a refreshing change. It's been ages since I focused on mobile design problems, and it felt great to flex those creative muscles again. How did I do? Looking forward to your thoughts!