HL10 PRODUCT UPDATE:
In January 2011, Plantronics changed the accessories included with the HL10 Handset Lifter. Plantronics eliminated the ring detection extension cable due to the low percentage of installed phones that actually required it. However, based on customer feedback, they have decided to reverse that decision. Plantronics will implement this change by the end of March 2011.
In the meantime, the ring detection cables are readily available, free of charge, through Plantronics Technical Assistance Center which can be reached at 1-800-544-4660.
Note: The lifters without the ring detection cable were manufactured from 1/6/11 through 3/25/11, and the corresponding date codes are 03/31/11 to 05/31/11.