Nowhere does Scripture speak of an explicit “inward call” (vs an “outward call”). More accurately, we see Scripture speak of one call1,2,3,4,5,6,7,8,9,10,11,12,13 that might be discussed at different times by inspired writers in terms that affect the individual inwardly1,3,4,5,7,8,11,12,13 and/or outwardly2,4,5,6,9,10,12.
By allowing Scripture to interpret Scripture we see that one may respond to the gospel call2,4,5,6,9. Those that respond with belief and obedience5,9,10,12 (and not just once7,8,13) are given God’s Holy Spirit as a dwelling3,8,9,11 and are subsequently encouraged to remain true to their calling1,3,4,6,7,8,10,11,12,13 until death. All of this together is “calling on the name of the Lord”.