Existing ad-hoc wireless communications systems are based around Wi-Fi communications, owing to the ubiquity and cost-effectiveness of Wi-Fi; no other open wireless communications channel offers the capabilities and benefits of mass-production consumer markets. However in some situations even long-range directional Wi-Fi links are not suitable. For example Pacific nations spread over island groups and archipelagos may have tens to hundreds of kilometers between population centers, coupled with a lack of areas of high elevation required to facilitate the longest range Wi-Fi links. In contrast, HF (High-Frequency) radios can facilitate communications over thousands of kilometers. We describe proof-of-concept integration of existing HF radio systems with the Serval Mesh, creating the opportunity to provide two-way secure text messaging and related communications services between communities separated by hundreds of kilometers, using heterogeneous radio links, without user configuration. Significantly, this proof-of-concept operates between Codan and Barrett HF radios, demonstrating that cross-vendor interoperability is possible, despite the incompatibilities that can arise between vendors in the HF space. The potential of this proof-of-concept was acknowledged by strong interest from the UN World Food Programme in seeing the integration of existing HF radio systems and the Serval Mesh to support humanitarian field operations.