In normal operation, a primary signaling controller in a first RAN manages bearer connectivity and tracking area updates for a UE and further interfaces with a second RAN over a primary signaling interface to facilitate inter-RAN signaling related to transition of the UE from being served by the first RAN to being served by the second RAN, such as circuit-switched fallback signaling. Upon detecting failure of the primary signaling interface, the first RAN is dynamically reconfigured to have such inter-RAN signaling for the UE pass over a secondary signaling interface between the second RAN and a secondary signaling controller of the first RAN, while the primary signaling controller continues to manage bearer connectivity and tracking area updates for the UE.