One or more media items can be bound to a voice call using a binding protocol. The binding protocol allows call participants to more easily transfer media items to other call participants using one or more user interfaces. A call participant can initiate a media transfer by selecting the media and a communication modality for transferring the media. The binding protocol can be active or lazy. In lazy binding, the call participant can select the desired media for transfer before the voice call is established, and subsequently mark the media for binding with the voice call. In active binding, the call participant can select and transfer the desired media item during the voice call, and the media item is automatically bound to the voice call. The media item can be transferred using a user-selected communication modality over an independent data communication channel.