This pen-phone is still a concept gadget. It has a a mono LCD screen to show numbers, a micro SD card to store data, a USB port to probably charge the phone and transfer data. The knob to activate the pen also works as a control wheel.

The pen-phone has a earpiece and microphone at either ends of the pen but is designed to be used with a bluetooth headset.

Don’t think that it would become popular but it reminds me of old spy movies where the agent uses his watch or some other device to make calls :D