Other dialing options include selecting from call history (which is also copied over from the phone and can be called up on the screen), by assigning and then selecting a speed dial number via one of the six preset buttons, or by manually entering a number one digit at a time using the joystick, which is probably the most time-consuming method. With a call under way, sound quality is clear and even: an option in the call menu lets drivers choose the speakers through which the incoming call audio is played. From the other end of the line, sound quality via the MEX-BT5100's mic is also reasonably clear, albeit a little tinny.
One of the best features of the MEX-BT5100 is the way it manages to integrate phone and music functionality into the same device while keeping the controls so simple. For audio sources, the stereo supports AM/FM radio, regular Red Book CDs, MP3, WMA, and ATRAC-encoded discs, and external sources via a rear-mounted auxiliary input. Those wanting to branch out can also invest in add-on modules for iPods and HD and satellite radio. When playing MP3 discs, the monochrome display can be configured to display a whole host of information including folder and track information, and tags for song, track, and artist information. While we like the ability of the system to display ID3 tag information, we are less impressed with the navigability of digital audio files, as there is no way to browse folder/song/artist information other than skipping through files one at a time. In partial mitigation of this, a one-touch shuffle function lets drivers play back discs in random mode. Like its predecessor, the MEX-BT5100 also comes with the ability to play audio streamed by the A2DP Bluetooth protocol.