The lightest cordless phone
It seems like another cordless handset, but the novelty of the Weightless Headset Phone is that the cordless phone is included in the handset; Despite this, it weighs less than 50 grams.
It works with standard technology in this type of phone (2.4 GHz) and has a range of about 30 meters from the base station, so you can be in the office all day without taking it off. The phone keypad is built into the earpiece, if you are skilled enough you can dial a number without removing the earpiece from your ear, but it doesn't seem very easy. As a curious detail, it has a light that alerts people around you when you are talking on the phone, so they know why you don't listen to them ...
By the way, you only need one ear for this earphone, so in the other you can put the Bluetooth earpiece of the mobile.
The price is 130 dollars (about 97 euros).