spent all weekend trying to figure out why my nokia 6600 won't work with my linux handsfree bluetooth emulator by trying all sorts of things like using 2.4.x kernels, flashing firmwares, different dongles etc. it turns out that the nokia 6600's handsfree audio gateway doesn't work. i tried it with anil's nokia 7610 and it works fine.
on bluetooth, apparently the broadcom dongles don't support SCO correctly (eg, no traffic comes out the other end of a sco socket.) under linux. in addition, it also requires you to have bluez-firmware so the module upload the firmware on modprobe (which i need to add to gentoo.)
D-Link DBT-120 Rev:B2 is the dongle to have if you're using linux because it supports everything. its even apple's preferred Bluetooth USB adapter. so you can get firmware updates from apple's site and use btdfu (bluetooth d??? firmware updater) under linux.
another interesting thing is that apparently there is no need to screw around with trying to decode CVSD. it seems that the decoding is done in hardware by the bluetooth dongle, so out of the SCO connection you actually get 8kHz 16-bit mono PCM. makes my life infinitely easier.
maybe after all this bluetooth hacking, i'll spend some time to spruce up and debug some of the gnome-bluetooth stuff so it is nearly as nice as the kdeblutooth package. finally, apple doesn't support SCO connections in their stack, so there's no way we can do what we're doing on a mac. arghh!