Am I Being Called To Be A Missionary?

This week on the Straight Truth Podcast, Dr. Josh Philpot has questions for Dr. Richard Caldwell about being a missionary. In one sense, every Christian is a missionary in that we are to share the good news of Christ with others. But most of us will never leave our country of birth to do that as our full-time vocation. So how does someone become a missionary? Is being a missionary based solely on someone having a desire for that work? Or, is there a specific call to be a missionary that is separate or distinct from a call to ministry work? How would someone know if they are being called to be a full-time missionary?