Can I use my headset while it is charging?

Yes. You can use your headset while charging it with the USB charging cable. 

Important
If a cable (e.g. a charging or audio cable) is connected to the USB port in the headset, you might notice a slightly elevated temperature around the USB port. A slightly elevated temperature is normal and within safety operating requirements and has no bearing on the lifespan or performance of the headset. If you however, experience that the headset generates significant heat or gets significantly warmer than usual when charging or in use, it is recommended to immediately stop using the headset and contact the Jabra reseller where you have bought the headset.