Mosuch Retro Telephone Handset 3.5mm Cell Phone Receiver for Cellphone Dark Blue;

Item Features:

Eliminates up to 99% of radiation absorption by distancing you from the cell phone
Works with most mobile devices with 3.5mm jacks; other adaptors available as accessories

Item Description:

Item Material: ABS
Measurement: 8" Long x 2.5" Wide x 2" Thick

Instructions:
First, plug in the handset directly into your cellphone. (the plug must be fully inserted). To ensure that the plug is correctly installed, you can wiggle the plug to prevent poor contact/static. 
Noise static may be due to bad signal in your surrounding environment; you may need to move to another location to use your phone to improve your phone connection (just as regular cells phones encounter static noise when there is bad signal). 
Apple iPhones can receive calls & adjust volume on the receiver, but Androids can only accept phone calls. 
This handset receiver can also be used for HTC, Samsung, MOTO, and most other mobile phone brands as the plug is quite universal & convenient.