why did my phone vibrate and show handset during call?

[ksanger35]

I have a Samsung S7 with Android 8.0.0. Today while I was on a call that I initiated my phone started vibrating and the status line at the top of the screen showed a flashing handset. I had never seen that icon before. I assumed I had an incoming call. However the phone app, recent calls, shows no missed calls. The Notification Saver app shows no notifications during the call. The battery is at 92%.

I had switched from the phone call to android to look up a message in Google Messages. The vibration and the flashing handset icon occurred while out of the phone application. I switched back to the application, and enabled speaker, then back to messaging, and got the vibration and flashing icon again.

This has never happened to me before. I would have remembered seeing the flashing handset at the top of the screen. Plus the noisy vibration too.

Can anyone explain why the phone would show me something that looks like an incoming call suddenly showing up?

 

[Rukbat]

A second incoming call won't show as a missed call - you can have only 1 call (unless you conference them - that's done at the central office, and you still have only 1 call - but with both people on it - only the person making the original call can add a call). When the second call comes in, tap the answer button and you'll be switched to that call, and the original call will be placed on hold. Red button to end the call you're on at the moment, and bring you back to the other call.

 

[ksanger35]

What's an answer button? Normally I answer by swiping right to left. When this happened I was in other applications and did not see any means to answer a phone call? I don't understand why the missed call does not show up. I didn't answer it. I had no indication of who was calling.