A secure three-way bridge in a SIP-based processing switch protects sensitive information provided by a party during a call with an agent in a contact center. During the call, the agent may bridge an interactive voice response system (“IVR”) onto the call using the secure three-way bridge so that the party can enter sensitive information, such as a credit card account, to the IVR. The information is provided by the party using dual-tone multiple frequency (“DTMF”) tones that are presented in an unmodified form to the IVR, but modified and then presented to the agent, so that the agent is unable to discern the sensitive information provided by the party. Other embodiments may accomplish similar capabilities by application of components outside of the bridging structure. Further, recording systems may record the call comprising the modified audio, thus protecting the sensitive information from subsequent detection upon review of the recording.