A number of Cisco phones have a 2.5mm headset jack. There are two different Plantronics cables that allow you to attach your Plantronics H-series headset directly your Cisco phones. The difference is the length. Cisco SPA cable P/N 64279-02 is 16 inches in length and the Cisco SPA / Polycom cable P/N 70765-01 is a coiled cable that stretches to a maximum length of 10 ft.
Use with the following Cisco Phones:
Use with the following Plantronics headset families:
2.5mm Headset Smartphone Adapter Cable Features: