In addition I would test the vision and see if the spirit that speaks contradicts God's written word and then I would pray and allow the Holy Spirit to testify to the truth or falseness of the vision. then I would have two or three trusted Christian brothers or sisters to hear the vision and pray and see if it really from God. then I would pray some more before acting upon the vision.
but that is more with prophecies then if God calls you to be a prophet
for in an extend I believe GOD calls ALL His children to be ministers of His love and speakers of His eternal promise of salvation thus speaking as oracles of God. Yet each individual's cal land life-long good work is assigned as God wills not as man wishes for it to be given unto them. Yet He is faithful to provide the skills and the talents and the people and the resourced needed for each ministry He ordains and lifts up.
2 Corinthians 6
Marks of the Ministry
1 We then, as workers together with Him also plead with you not to receive the grace of God in vain. 2 For He says:
“ In an acceptable time I have heard you,
And in the day of salvation I have helped you.”[a]
Behold, now is the accepted time; behold, now is the day of salvation.
3 We give no offense in anything, that our ministry may not be blamed. 4 But in all things we commend ourselves as ministers of God: in much patience, in tribulations, in needs, in distresses, 5 in stripes, in imprisonments, in tumults, in labors, in sleeplessness, in fastings; 6 by purity, by knowledge, by longsuffering, by kindness, by the Holy Spirit, by sincere love, 7 by the word of truth, by the power of God, by the armor of righteousness on the right hand and on the left, 8 by honor and dishonor, by evil report and good report; as deceivers, and yet true; 9 as unknown, and yet well known; as dying, and behold we live; as chastened, and yet not killed; 10 as sorrowful, yet always rejoicing; as poor, yet making many rich; as having nothing, and yet possessing all things.