A voice gateway is the correct device to configure in this scenario as it functions to connect traditional telephony networks to VoIP networks, enabling the use of analog phone systems over a digital data network. In essence, it translates between the different protocols used in public switched telephone network (PSTN) and VoIP systems, thus facilitating seamless communication between the two. A wireless LAN controller is used to manage wireless access points and is not related to telephony. A load balancer distributes network or application traffic across several servers to improve responsiveness and availability, but it does not translate telephony protocols. A media converter, conversely, is a device that converts one type of media to another, such as fiber to ethernet, but it does not handle VoIP or analog telephone signals.