The ion transport properties of glasses and supercooled melts are studied using the scaling properties of complex conductivity data. It is shown that the frequency response of the conductivity reflecting the transport mechanism is very similar in glasses and in melts. In the crossover regime from de to dispersive conductivity, the frequency response depends on composition, while a universal response is found at higher frequencies. The outcomes of an alternative analysis based on the complex electrical modulus formalism are examined in detail, and it is demonstrated that the shape of the M" peak is not significant with respect to the ion transport mechanism.