We paired the iTech SolarVoice 908 with the Apple iPhone 3G. Call quality was fairly good on the whole. Incoming quality was very good, with clear and natural sound and little static. We did have to adjust the volume occasionally, but it wasn't too bad. Callers reported slightly harsher quality on their end, but could still hear us just fine. The quality did diminish a bit when we were in an especially noisy environment. For example, we tested the headset outside in the rain, and callers had a harder time hearing us.
Features of the headset include the typical call answering, ending, and rejecting, last number redial, call-waiting support, voice dial support, and the capability to transfer calls from the headset to the phone and vice versa. It also has multipoint technology, which lets it connect up to two devices at once, plus A2DP streaming in case you want to listen to music. It won't offer stereo quality, of course, but if you don't want to bother reaching for your headphones, this works for occasional listening.
If you don't have the chance to solar charge it, the iTech SolarVoice 908 has up to 5 hours talk time and up to 5.83 days standby time. Theoretically, it has infinite standby time in optimum sunlight, but as we said above, that isn't always possible. The headset comes with a desktop cradle that you can position on your car's dashboard or anywhere that gets the best sunlight.