Be specific about asking for your phone appointments. Avoid phrases like “Well what would be a good time for you?” or “Yes we should talk sometime”.  Send something to the effect of “I am available for a ten-minute meet-and-greet call on Tuesday at 9 AM or Thursday at 3 PM.  Which one works best for you?

If you use a scheduling program like Calendly then you can also send the link, although my experience is that only a small percentage of people schedule this way.