1) Which Apple computers work with the microphone and volume controls that are included with the Apple Earphones with Remote and Mic?

Any computer that displays "External microphone" in the System Profiler will work with the Apple Earphones with Remote and Mic. To confirm that External microphone is in your System Profiler, choose About This Mac from the Apple () menu and then click More Info. Select Audio (Built In) under the Hardware section.

2) Is there a way to tell that my system detects my earphones?

Yes. From the Apple () menu, choose System Preferences. From the View menu, choose Sound. While your earphones are connected, click the Output tab; Headphones should be listed as the output device. Click the Input tab to confirm External microphone is selected as the input device.

3) Is there a way to tell that my system can use the external microphone?

Yes. From the Apple () menu, choose System Preferences. From the View menu, choose Sound. If there is an "External microphone" listed in the Input tab, your computer can use the microphone included with Apple Earphones with Remote and Mic.

4) Do I have do something special to enable all the features offered with these earphones?

No, just plug them in. The audio out to your earphones and the audio in to the microphone will switch automatically when your computer detects them.

5) Sometimes the volume controls or microphone don't seem to work after I've plugged them in to my computer. How can I change this?

You might have held down the volume control switch while plugging them in. This can cause the volume controls or microphone to function in unexpected ways. Unplug the earphones from the computer and plug them in again, taking care not to press the volume control switch while doing so.

Apple Earphones with Remote and Mic

[Source: Apple Technical Articles]