With the app’s built-in dialer in the Calls tab, you can use your regular phone plan to start making calls to anyone (regardless of whether or not they use Truecaller). If any of your contacts also use the app, you can make a data call to them using its HD Voice Call feature. Just go to the Calls tab, tap the phone icon above the dialer button, then select a contact.
Want to chat with a group? Tap “Voice Call,” followed by “Create group Voice Call,” then select up to seven participants from your contacts. Alternatively, add more people during a call by tapping the plus symbol at the top right of the screen.