The iPhone headset from Apple can work with Elgato Thunderbolt™ 2 Dock as basic headphones.

The iPhone headset has a few special features that will not work with Elgato Thunderbolt™ 2 Dock.

 

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Headphone Jack of Elgato Thunderbolt™ 2 Dock

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You can use the iPhone headset as headphones, if you connect it to the headphone jack of Elgato Thunderbolt™ 2 Dock.

You cannot use the transport buttons (move forward, move back, pause) or volume buttons.

 

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Microphone Jack of Elgato Thunderbolt™ 2 Dock

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You cannot use the iPhone headset as a microphone. 

If you connect it to the microphone jack of Elgato Thunderbolt™ 2 Dock then it won't work at all, as headphones or a microphone.