Sometimes it happens when you are sitting in an important meeting and your phone start ringing. It is very embarrassing situation and you want to switch the phone to silent mode as quickly as possible. In iphone there is a shortcut for this which is very easy and saves you from such incidents. The trick is simple;
Hit either of the volume buttons and your iphone will be muted in no time. But the call will not transfer to the voice mail. This trick is applicable only in case of incoming calls, for other calls the phone will ring. Remember that this only affects that particular incoming phone call; other calls will still sound the ringer.
If you want all calls to be silent, just hit the mute switch on the side of the iPhone.
There are so many apps now available in the market handle the profiles by using motion sensors in smart phones. You just need to invert the iphone upside down and the phone will turn it to silent mode.