[. . . ] Plantronics Ltd Interface Business Park Bincknoll Lane Wootton Bassett Wiltshire SN4 8QQ ENGLAND Tel: + 44 1793 842200 Fax:+ 44 1793 848853 Plantronics Denmark Anderson Nexø vej 29 2860 Søborg Denmark Tel: +45 3955 1051 Fax:+45 3955 1052 Plantronics B. V. [. . . ] To obtain maximum performance, please read the adapter installation and usage information contained in this user guide. For information on headset operation please refer to the user guide supplied with your headset. If you have any questions, please contact Plantronics Customer Services on Tel: 0800 410014 SAFETY INFORMATION The headset adapter is suitable for use with any Plantronics H series Ultra headset. The Charger headset adapter is powered via the transmit lines by the host equipment. The standard operating current range for the headset adapter is 15mA to 100mADC. Caution: This headset adapter may not operate satisfactorily with all types of telephone apparatus. [. . . ] (Fig A. 1) Volume Control Fig A. 1 B Setting the Volume Control To set the volume control to the listening level most comfortable for you, start with the wheel turned to number 1, the lowest level. [. . . ]