Enhanced routing of an authentication, authorization, or accounting-related message between a local access network being accessed by a roaming mobile terminal and a home service network is described. The spring conductor has first and second rising arms with a midsection therebetween. In the first drive mode, the piezoelectric element is driven at a first speed, and is held to a first voltage V1 in a first hold process during a first time defined based on a natural period Tc.