A wireless cassette adapter in the form of an audio cassette that can be inserted into an audio cassette player provides an audio interface for wireless mobile devices to existing audio systems. A wireless interface is established by the wireless cassette adapter to one or more wireless mobile devices and receives audio (including voice) data from the wireless mobile devices. The cassette adapter processes the audio data and transfers the data in analog format to the cassette player which is connected to an existing audio system which plays audio data from the wireless mobile device. Furthermore, the cassette adapter receives voiceinput that is transmitted to the wireless mobile device as part of a telephone call or in performance of voice recognition performed at the wireless mobile device.