Recent calls
The menu displays received/missed incoming/outgoing calls. Here you also can call the required device or open the lock/s.
Missed calls are displayed in red color.
Photos are not saved for every call. They are created when the app receives a video stream and the stream remains active for a minimum time:
iOS — after 3 seconds of an active video stream;
Android — after 5 seconds of an active call with media.
The photo depends on when the media stream starts, not strictly on whether the call was answered. If early media is available, a photo may appear even for missed calls.