Test the waters by either hitting a button or asking your portal to check whether (contact's name) wants to receive a call right now, to avoid cold calling them or having to text first to see if they're ready.
Ideally this would produce an audible & visible notification on their portal that they could then respond to with: Yes please call, No I am busy, Give me 5 minutes, or a custom message.
Since calls can be initiated and answered by voice, this feature should be voice enabled on both ends too. But a visual interface would be better than nothing.
This would be a feature that I'd use every time I called someone, and it would encourage me to reach out to more of my contacts, more often.