The ac impedance $Z=R+j\ensuremath{\omega}L$ of a metallic soft magnetic wire with periodic circular domains relevant to domain-wall displacements is calculated and compared with the classical model relevant to domain magnetization rotations (DMR). It is shown that the magnetoimpedance (MI) defined as the relative change of $|Z|$ with a longitudinal dc field ${H}_{\mathrm{dc}}$ at a fixed high frequency will have large values when the circular magnetization process is dominated by DMR. The single and double-peak $|Z|$ vs ${H}_{\mathrm{dc}}$ behaviors are explained and some experiments for studying MI of amorphous wires are proposed based on the model results.