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)
Select the i beside the number and select Block This Caller. On an Android, go into your dial screen > Settings > Call > Caller Rejection > Auto Reject List, and from there you can add numbers to the list of blocked callers. Or, go to your dial screen > Recent, and find the recent caller whose number you want to block.