A voice gateway is used to transmit voice signals through the Internet. The communication session is sequenced to occur at designated periods provided by the end user andor an administrator, while maintaining end user anonymity. The input data stored in the deinterleaver memory is read at a read address generated based on the synchronous counting value. The locking device is disposed between one of the side rod sections and a corresponding one of the seat rods, and includes an angle-limiting mechanism and an actuator operable to cooperate with the angle-limiting mechanism so as to adjust the footrest among a plurality of angular positions including an erected position whereat the stroller is connectable with the car seat. Free trade qualification traverses the bill of materials to calculate whether a given finished product is qualified.