If you want to turn the Modus 3500 into a stereo headset, simply plug in the included stereo earbuds into the headset's charger jack. It's too bad that there isn't a 3.5mm jack so that you can use your own headphones, but maybe Samsung will release an optional attachment in the future. The stereo earbuds have soft silicon covers that are designed to fit a little snug in the ear, which we like. The earbud cable has a microphone so you don't have to unplug the earbuds every time a call comes in. Also on the cable is a little clip so you can attach the wire to your shirt. If you want, you can attach a shirt clip on to the headset as well. We would recommend doing this, as your headset might flop around a lot if you don't.
Features of the headset include the typical answering, ending, and rejecting calls, last number redial, call waiting support, voice command support, and multipoint technology, which lets it connect up to two devices at once. Of course it also has A2DP, which lets you listen to streaming stereo music. Unfortunately, we discovered we couldn't actually use the headset to play or pause music, only to manage calls. We still had to control our music using the phone.
We tested the Samsung Modus 3500 with the Apple iPhone 3G. Call quality was quite good for the most part. Thanks to the headset's dual-mic noise-canceling, we were able to field calls even in relatively noisy situations, like in a crowded cafe during lunch. We had little problem hearing our callers, though callers did say that they heard a bit of static and crackling at times. Also they said that though they could hear us, our voice quality sounded rather harsh and machine-like. As for listening to music or podcasts, the audio quality was good. Nothing groundbreaking, but it works well enough for our nonaudiophile ears. There was a decent amount of bass and good stereo sound. Our only caveat is with where you place the phone; we found that if we put it in our back pocket, the Bluetooth connection would cut out intermittently. We're not sure if it was because of the distance or the constant movement. It's a bit of a letdown, but as long as we placed the phone in a front pocket or purse, it seemed to work as intended.
The Samsung Modus 3500 has a rated talk time of 6 hours, a rated play time of 6 hours, and a rated standby time of 7.5 days.