ConnexLinks of the same family can communicate over the air, despite different physical interface. So a CL4490-1000-232 can communicate with a CL4490-200-485 or a CL4490-USB. They cannot communicate with ConnexLinks of other families, a CL4490-1000-232 cannot communicate with a CL4790 or a CL4424. ConnexLink USB versions are made to interface with a PC, they cannot act as a USB host device and a pair of ConnexLink USBs cannot act as a USB bridge. 900Mhz radios, such as the CL4490 and CL4790 are approved for use in North America.