This is one of the coolest feature of 'Interrupt'. Any of your friend who don't have android can also make your phone ring even if its in silent mode. This is very useful when people want to talk to you urgently and notify as soon as possible.
Your friends can send a special message to you and then make a phone call that's it.
Ask your friend to send '=i=' in message and once the message reaches you then ask them to dial your phone number. Your phone will start ringing even though its in silent mode making the incoming call as Interrupt/Important call. Try it and pass on following instructions to your friends.
Instructions for your friends to make an interrupt call if they want to reach you urgently.
"If you wish to reach me urgently, just send me a message with =i= and then make a phone call. My phone will start ringing even if its in silent mode. I have installed Interrupt android app that does the magic!" Paste this as your Facebook status :-)
You can use this if you missed place your phone in silent mode and wish to ring it loud. Try it!