If you want the added freedom of being able to use both your hands whilst still talking on your mobile phone; then a cell phone hands free headset is just the accessory to choose.
The traditional cabled version of cell phone hands free headsets, with their speaker and microphone, can be attached by a cable to the 2.5mm headset jack on your cell phone.
These older type headsets are cheap, and simple. But if the need for a long and loopy wire could drive you well, just as loopy, then you should consider paying a bit more for Bluetooth.