Samsung SPH-D720ZKASPR - Manual (Page 11)

Your phone and accessories 11
NSOG-S-1.1-001 Nexus S 4G Owner’s Guide
Using the stereo headset
The stereo headset plugs into the phone’s 3.5mm headset jack.
You control the headphones’ volume with the phone’s Volume Up/Down button and
with the applications on your phone (as described in the Android User’s Guide and in
the documentation for your applications).
Headphones
3.5mm headphone jack
Microphone