Availability of a call for a mobile device can be signaled over a data channel; to avoid unnecessary airtime charges, an audio channel for the voice call is setup only if a user of the mobile device accepting the call. Responsive to the user accepting the call, the mobile device can signal to a network to establish the audio channel. Establishing the audio channel takes some time. The time in which the audio channel is established is used to output, at the mobile device, supplemental information received over the data channel, such as information about a calling party, such as directory information, organization information, and call history. The outputting of such information during this time period makes a user experience better, because the user is less likely to think that a call has failed by observing an unfilled delay between when the call was accepted through the user interface and when the audio channel is actually available to service the call.