One intelligent headset to manage your PC, mobile and desk phone calls. Automatically routes calls to the mobile phone or headset, whichever device is within easy reach. One-touch call answer/end, vol +/-, mute and flash controls across devices. Conference in up to three additional headsets and guests can continue through multiple calls. Note: If you plan to use this headset and the Electronic Hook Switch Cable with a VoIP phone, we will need to make an adjustment on your phone in the Call Manager. Please send email to firstname.lastname@example.org stating: Adding W740 to phone number 734-xxx-xxxx (your 10-digit phone number).