11 And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers;
Apostles and prophets are synonymous terms and were sent by God;
Luke 11:49 Therefore also said the wisdom of God, I will send them prophets and apostles, and some of them they shall slay and persecute:
1Timothy 2:7 Whereunto I am ordained a preacher, and an apostle, (I speak the truth in Christ, and lie not;) a teacher of the Gentiles in faith and verity.
Nehemiah 6:7 And thou hast also appointed prophets to preach of thee at Jerusalem, saying, There is a king in Judah: and now shall it be reported to the king according to these words. Come now therefore, and let us take counsel together.
Luke 16:16 The law and the prophets were until John: since that time the kingdom of God is preached, and every man presseth into it.
In fact, prophesying is preaching;
Acts 21:9 And the same man had four daughters, virgins, which did prophesy.
Romans 12:6 Having then gifts differing according to the grace that is given to us, whether prophecy, let us prophesy according to the proportion of faith;
1Corinthians 13:9 For we know in part, and we prophesy in part.
Here, we can see the synonymous relationship between pastor and teacher. A pastor is supposed to be a teacher, as well.
1Timothy 3:2 A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach;
2Timothy 2:24 And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient,
Timothy, a young pastor, is key here to understanding the meanings of these words; pastor, teacher, and evangelist.
Timothy is not only a bishop or pastor, but does the work of an evangelist in preaching the gospel.
2Timothy 4:5 But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
It appears to me from reading the Bible literally that the Prophets of ancient Israel went out preaching a warning about what was to come while the Apostles of Christ preached that Christ had come. Both of these offices and callings were to the community and the world at large. Evangelists, Pastors, and Teachers appear to be directed to operate within the church body itself.
So, when you do the work of a Prophet or an Apostle it is outside of the confines of the body of Christ but when you are doing the work of an Evangelist, Pastor, or Teacher you are working within the church, among the saved.
I certainly understand if you disagree. Some assumptions have to be made on these definitions as the Bible in this regard is written as if assuming this knowledge is common within the church.
The important thing to remember is that these callings are given from God, not career choices.