Methods are disclosed for detecting feature interactions during a call that has a signaling path comprising two or more legs. In accordance with the illustrative embodiment, feature state information is maintained for each of the legs of the call and is propagated along the signaling path. The illustrative embodiment is capable of detecting interactions between features in different legs of a call, as well as interactions between features in the same leg of a call. Moreover, the illustrative embodiment is capable of accommodating a variety of feature resolution techniques. In one illustrative embodiment specific to Voice over Internet Protocol (VoIP) telephony, a Back-to-Back User Agent (B2BUA) stores and propagates the feature state information, and performs address mapping for two specially-defined headers in addition to the usual Session Initiation Protocol (SIP) headers.