Main article: Multi-user MIMO. Recently, results of research on multi-user MIMO technology have been emerging. While full multi-user MIMO (or network MIMO) can have a higher potential, practically, the research on (partial) multi-user MIMO (or multi-user and multi-antenna MIMO) technology is more active.
There are two ways to decline a call on the iPhone. 1  By pressing the Sleep/Wake button. 2  By tapping the 'Decline' button onscreen (appears only when the phone is unlocked, as you've mentioned)
To avoid the interruption and the irritating beep sound, you can turn off Call Waiting on Your iPhone by doing this: Go to the Settings app on the iPhone. Tap on Phone. Now select âCall Waitingâ feature and wait for the loader to show the switch. Swipe the Call Waiting switch to OFF.