A high-energy ball-milling process was applied to the preparation of silver ion conductors from the compositions 80AgI . 20Ag(3)PO(4) and 60AgI . 40Ag(3)PO(4) (mol%) the composition 80AgI . 20Ag(3)PO(4) corresponds to that of the crystalline Ag7I4PO4 superionic phase, and the composition 60AgI . 40Ag(3)PO(4) is reported as a typical composition of the superionic conducting glasses in this system. For the composition 80AgI . 20Ag(3)PO(4), ball milling for longer than 190 h led to the formation of an unknown new crystalline phase, and the new phase showed a high ion conductivity of 6 x 10(-2) S cm(-1) at room temperature. The conductivity is higher than that of the crystalline Ag7I4PO4 phase. The ball-milling process for the composition 60AgI . 40Ag(3)PO(4) made it amorphous, and the ball-milled sample showed a high ion conductivity very similar to that of melt quenched glass with the same chemical composition.