The calling into the prophetic ministry was always initiated by sovereign prerogative of God according to the scripture. The first step in the process is the divine revelation of God to the individual through a supernatural intermediary such as angels or through the medium of dreams and visions and/or through the anointing of an established prophet. What this implies is that an individual cannot be legally a prophet through self-ordination or institutional ordination. The privilege of a true prophet is special access to divinely classified information which is unknown by others.

“And He said, “Hear now My words: If there is a prophet among you, I the Lord will make Myself known to him in a vision And I will speak to him in a dream”. Numbers 12:6 (AMP)

“Now the word of the Lord came to me, saying, 5 Before I formed you in the womb, I knew you [and approved of you as My chosen instrument], And before you were born, I consecrated you [to Myself as My own]; I have appointed you as a prophet to the nations.” Jeremiah 1:4-5