To be called of God is to receive an appointment or invitation from him or his duly authorized Church leaders to serve him in a particular way.

He laid his hands upon him and gave him a charge, Num. 27: 23. I ordained thee a prophet, Jer. 1: 5. I have chosen you and ordained you, John 15: 16. Paul was called to be an Apostle, Rom. 1: 1. No man takes this honor unto himself, but he that is called of God, Heb. 5: 4. Jesus was called of God after the order of Melchizedek, Heb. 5: 10. I have been called to preach the word of God according to the spirit of revelation and prophecy, Alma 8: 24. Priests were called and prepared from the foundation of the world, Alma 13: 3. If ye have desires to serve God, ye are called, D&C 4: 3. Stand fast in the work to which I have called you, D&C 9: 14. You need not suppose that you are called to preach until you are called, D&C 11: 15. Elders are called to bring to pass the gathering of the elect, D&C 29: 7. No one shall preach my gospel or build up my Church unless he is ordained, D&C 42: 11. There are many called, but few are chosen, D&C 121: 34. Man must be called of God, A of F 1: 5.