This document is about the Polycom IP 331 Phone User Guide. It describes the basic phone features such as making, answering, and ending calls, muting the microphone, holding and resuming calls, redialing numbers, transferring calls, call forwarding, speed dialing, using Do Not Disturb (DND), voicemail, viewing call lists, three-party calls, university directory, customizing the phone, contact directory, adjusting speaker and ringer volume, and customizing ring tones.