We paired the Jabra BT8040 with the RIM BlackBerry Pearl and the Helio Mysto. Pairing process was smooth with both phones, taking less than a minute with each. Call quality was excellent--nearly zero echoes were heard, and callers reported a smooth and clear sound from our end. We also heard our callers very well, with plenty of volume without it being too loud. This might be because of the number of audio-enhancing technologies the BT8040 has, such as Active Noise Reduction, Intelligent Volume Settings (equalizes the audio volume), and Acoustic Shock Protection, which protects the ear from a sudden loud spike in volume. Even though we did get a tiny bit of static occasionally, and it didn't block out a lot of background noise, the overall call quality was great.
As we mentioned above, the BT8040 also streams music wirelessly. Since it's a mono headset, we couldn't get a full stereo listening experience, and the music quality was predictably lack luster. But it did stream music when we wanted it, and that's all we expected from it.
The Jabra BT8040 has a rated battery life of 6 hours of talk time and 8.3 days.