As of now, the features of the App are:
✓ You can set 'knock words' for either all of your contacts, or starred contacts only, or for selected contacts.
✓ You can change the active time of a knock word, that is, once a Knock word is received via SMS, the time for which the App will allow the number to ring your phone could be set by user.
✓ You can set different keyword for different contacts.
Additional feature in future version:
✓ When a call is received from a person multiple times, the phone will automatically send an SMS stating that the user's phone is now in silent/vibrate mode and if it's urgent he/she may send an SMS "urgent" and then call to ring.
✓ Checking for pattern of words in SMS.
✓ Configure the sound volume to ring at.
✓ History of contacts who used knock words
✓ History of contacts who have been trying to reach you a lot of times but didn't use Knock words (most likely that they don't know about it.)
✓ You may expect integration with WhatsApp and other services' messages as an option.