The prayer ministry has to do with ministering to people - Believers and unbelievers - through prayer, intercession, and supplication. Every Believer in Christ Jesus has a level of ministry in prayer towards people - both to the Saints and the sinners. You pray for the people you preach to; and you pray to God to help this or that person in one area or the other. However, there are people who have greater responsibility, in ministry and assignment, to pray for different kinds of people and for the Plan and Purpose of God to come to pass on this earth. Of course, this does not mean that prayer is (or must be) the only ministry that the person has; because an apostle, a prophet, an evangelist, a pastor, a teacher, a deacon, a musician, an usher, and others can have a strong call in praying and interceding for people, communities, churches, ministries, regions, and nations.