Radio frequency (RF) communication, while reliable, is capacity limited and faces heavy spectrum regulation. In contrast, free space optical (FSO) communication provides multi-Gbit/s rates without spectrum allocation. Yet, FSO communication experiences link degradation due to clouds, fog, beam misalignment, and line of sight blockages. This paper reviews the development of a layer 2 modem that combines both RF and FSO links seamlessly with error-free transmission and quality of service (QoS) capabilities. Test data collected on a 30 km terrestrial link demonstrates mode m integration with a commercial RF link and provides insight on the QoS system performance.