Joint sensing-communications systems can be designed based on four different types of system integration. These different levels range from complete isolation, to complete co-design of systems. Some levels of integration, such as non-integration (or isolation) and coexistence, are not complex in nature and do not require an overhaul of how either sensing or communications systems operate. However, this lack of complexity also implies that joint systems employing such methods of system integration will not see significant performance benefits on achieving RF convergence. As such, non-integration and coexistence methods are more short-term solutions to the spectral congestion problem. In the long term, systems will have to be co-designed together to see significant improvements in joint system performance.