How to open all numbers from WhatsApp directly in Truecaller I'm part of some WhatsApp groups and there are people whom I know but unable to map them to those phone contacts which does not show anything but blank profile photos and no name.

Asking everyone will be too much work.

This is too much frustration.

Is there anyway to directly open the contacts in Truecaller instead of the default android app?
The simple way to get people details for WhatsApp messages is to use Auto-Search in Truecaller by allowing Notification access to Truecaller
Go to Truecaller->Settings->General->Auto-Search and switch Messaging apps to ON 
And whenever you get a message from person who is not in your contact list, you will get a notification like:

WORKS FOR MESSAGES FROM GROUPS TOO.
YOU WILL GET NOTIFIED ONLY WHEN SOMEONE SENDS YOU A MESSAGE(CAN'T FETCH ALL UNKNOWN CONTACTS FROM WHATSAPP GROUP).
ALLOWING NOTIFICATION ACCESS IS A DANGEROUS PERMISSION


  Truecaller will be able to read all
  notifications, including personal
  information such as contact
  names and the text of messages
  you receive. It will also be able to
  dismiss notifications or trigger
  action buttons they contain.
  This will also give the app the ability
  to turn Do Not Disturb on or off and
  change related settings.



P.S. WhatsApp does shows names(which user has set in his WhatsApp profile) in group info for each person.