A user equipment (UE) and an Internet Protocol (IP) Multimedia Subsystem (IMS) node may exchange fallback indicators in SIP signaling for purposes of controlling fallback procedures implemented by the UE. The SIP signaling may include a SIP request from the UE that includes first information. The IMS node can evaluate a criterion based on the first information, and, if the criterion is met, the IMS node may authorize (or prohibit) the use of a UE-supported fallback radio access technology (RAT) that corresponds to a fallback indicator also included in the SIP request. Based on the evaluation of the criterion, the IMS node may respond to the UE with a SIP response that includes second information indicating which of the supported Fallback RATs the UE is authorized to use (if any), and which of the supported Fallback RATs the UE is not authorized to use (if any).