Enhanced communications over a Universal Serial Bus (USB) Type-C cable are disclosed. In one aspect, a link control circuit is provided in a USB host to enable one or more communication circuits in the USB host to transmit and receive protocol-specific data over a sideband use (SBU) interface according to communication protocols that may or may not be USB compliant. In another aspect, the link control circuit is provided in a USB client to enable one or more communication circuits in the USB client to transmit and receive protocol-specific data over the SBU interface according to communication protocols that may or may not be USB compliant. By configuring the USB host and the USB client to support multi-protocol communications via the SBU interface, it is possible to enable more flexible architectural design in mobile communication devices for enhanced performance and reduced costs.