This Cable is designed to be used with Poly/HP H-Top headset to the dedicated Headset jack on most phone, therefore bypassing the need for an amplifer. 
 
Coil cable extends to 10'.
 
Looking for an alternative, check out the JPL BL-12+P
 
https://www.headsets4business.ca/product-page/jpl-bl-12-p-bottom-lead-with-plx-compatible-qd