Previous simulations have shown substantial performance gains can be achieved by using hybrid cellular and wireless LAN (WLAN) approaches . In a hybrid system, a proxy in an area of strong connectivity (and therefore higher bandwidth) forwards traffic on behalf of a client in an area of weaker connectivity (and therefore lower bandwidth). The proxy routes traffic between the base station (over a cellular link) and the client (over a WLAN). Such approaches have had limited practical applicability due to substantial security risks, including eavesdropping, intentional performance degradation and cheating the incentive schemes. The Secure Unified Cellular Ad Hoc Network (SUCAN) protocol is designed to address these risks, allowing the deployment of hybrid networks. SUCAN uses incentives and cryptographic techniques to eliminate cheating by self-interested hosts, while limiting the damage caused by malicious hosts. We implemented SUCAN on Verizon's Broadband Access network. To our knowledge, this is the first real-world implementation of a hybrid cellular network protocol. Our implementation results show that the SUCAN system can provide substantial performance increases and protects against performance degradation even in the presence of malicious behavior.