We received a few HTC ExtUSB connectors from PodGizmo. The first thing we thought of, was making the T-Mobile G1 send the audio to an iPod Speaker set we have. There is a sea of iPod accessories, so naturally the dock connector has a well known pinout. Figuring out the pinout for the HTC ExtUSB connector wasn’t too hard, I just split open my hands free adapter I got with my T-Mobile Dash.
Connection a T-Mobile G1 to an iPod dock