br br Avaya one-X Deskphone telephones set the new standard for end user productivity with high fidelity audio, an intuitive context sensitive display, phone models designed specifically for user profiles, and a modular, flexible architecture allowing for enhanced total cost of ownership. With the latest release of SIP telephone firmware, the Avaya 9640 telephones deliver best-in-class SIP telephony along with powerful application capabilities. Upgrading to the SIP version of phone firmware for 9600 Series telephones is simple and free of charge – providing great flexibility and investment protection.