Polycom C16 - Manual (Page 146)

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
5 - 66
The telephony channel controls are shown in the following figure.
Phone Connect
The telephone interface may be taken off hook by pressing the phone button
on the controls page. Once the telephone is off hook, digits may be dialed by
pressing the keys on the keypad.
Please note that the telephone must be taken off hook before digits may be
dialed. This behavior is different from the Vortex products where dialing
digits if the phone were on hook would cause the phone to go off hook. With
the SoundStructure products, the phone must be taken off hook prior to
dialing.
Auto Answer
Auto answer enabled will cause the SoundStructure device to answer the
phone automatically after two rings.
Entry Tones
Entry tones enabled will cause the SoundStructure device to play a short series
of tones into the local room to indicate that the phone has been answered.
Exit Tone
Exit tones enabled will cause the SoundStructure device to play a short series
of tones into the local room to indicate that the phone has been hung up.