Called to him for called, A.V. The R.V. gives the force of the middle voice μετεκαλέσατο. The elders of the Church; viz. of Ephesus. These are manifestly the same as are called ἐπισκόπους in Acts 20:28, "overseers," or bishops.
The distinctive names and functions of Church officers were not yet fixed; and the apostles themselves, aided by degrees by such as Timothy and Titus, were what we now call bishops, exercising oversight over the elders themselves as well as over the whole flock (see 1 Timothy 3:1).
The diocesan episcopate came in gradually as the apostles died off, and the necessity for a regular episcopate arose (see Acts 6:1-6; Acts 14:23, etc.).