I've been using the Sendstation dock extenders successfully for both my 3G and 3GS on a universal dock and Yamaha Receiver iPod dock for several years now. Never had an issue with any case. Apple's own bumper case has an opening around the 30 pin connector that is too narrow. This prevents the sendstation adapter from seating correctly. Works fine with the case off. Additionally, the slightly wider 30 pin connectors Apple sold individually and with the 3G (not 3GS) and iPod products prior to 2009 will also not fit. Plastic is too wide at the base, I'm thinking the cheaper solution will be to dump the bumper and go with another case.