Nowadays, several wireless communication solutions targeted at low-power devices (e.g. sensors, actuators) compete for market dominance. As a consequence, the deployment of the Internet of Things is slowed by fragmentation. However, Cross-Technology Communication (CTC) has appeared as a solution capable of bridging the compatibility gap between non-interoperable devices. In this way, we propose using Wake-up Radio (WuR) to achieve high rate bidirectional CTC, introducing WuR assisted CTC (WuR-CTC). Although WuR was originally proposed to reduce radio power consumption, it provides a secondary communications channel that can be used for high-speed and bidirectional CTC. With WuRCTC, we demonstrate that WuR can lead to interoperability between non-compatible wireless devices, therefore, providing a compelling reason for the harmonization of the nascent WuR specifications. This article presents a WuR-CTC solution implemented on an heterogeneous testbed with IEEE 802.11 and IEEE 802.15.4 devices. The resulting testbed achieves reliable CTC with an effective throughput of 26.7 kbps. Moreover, the addition of WuR to the testbed devices provides energy savings, and, in a clear advantage over traditional duty-cycled solutions, allows devices to asynchronously maintain communications.