The Primary Role of Prophets

I think etymologically the word, or the most common word, for prophet in the Old Testament, nabi, is correctly understood as a passive noun form from a verb which must have meant "to call," and so a prophet was one who was called. In context of the prophets, prophets are those who are sent; that is, they are called in the sense that they are called to a commission. Prophets are commissioned. But in actual usage, I think when the Old Testament uses the term nabi, it's especially in close association with the prophet speaking and speaking the words of the Lord.