What should I tell obsessed guy won't stop callingg me?

I met a guy couple months ago he's older divorced w adult children. He told me about his army days back in the day said he has never shared all the gory details and feelings before. I gave him my number but bec he lives far away and other factors I don't want to see him. He's a big strong guy so I don't want to upset him. He's been calling every ten minutes for past couple hrs I only listened one msg he says I haven't made effort to see him etc. Should I answer the phone since he won't take a clue I'm not interested as I flaked last time after he called nonstop like this and how I avoid his calls. What should I do?