Voice-coded in-band data for interactive calls

A voice-coded in-band communication device monitors a voice-coded channel to detect data to present to a user. During operation, the communication device can detect a data-encoding signal from the voice-coded channel, such that the voice-coded channel can carry an audio signal that includes a voice signal and the data-encoding signal. The device decodes the data-encoding signal to detect a data element. The data element can include information that is to be presented to a local user, a request from a remote device for information about the local user, or information that the system can use to establish a peer-to-peer connection with the remote device over a separate data channel. The device can also generate a filtered audio signal to present to the user by removing the detected data-encoding signal from the voice-coded channel, and then reproduces the filtered audio signal for the user.