Troubleshooting the Polycom CX300 Phone
 Draft 1  9
• Check settings in the Sounds application of Control Panel in the Windows 
operating system. If the Sound is set to No Sounds, the phone will not give 
you a dial tone even if the speakerphone is turned ON. Change the sound 
setting to Windows Default. The same applies when the Windows 
computer speaker is set to zero or mute. Increase the speaker volume 
setting on the computer.
• Test that you can hear a dial tone from the speaker. Place the handset on 
the cradle and press the Speaker button. Press the Playback volume + 
until you can hear the dial tone.
When you lift the handset:
• Make sure that the handset cord is attached correctly to the handset jack 
(not the headset jack) at the back of the phone. Also, make sure that the 
handset is connected correctly to the handset cord. A ‘click’ sound 
indicates that the cord is connected correctly.
• Check that the handset volume level is high enough to be heard. While 
holding the handset to your ear, press the Playback volume + until you 
can hear the dial tone.
When you press the headset button:
• Check that the headset is compatible with the phone. For more 
information about headsets, refer to 
http://www.polycom.com/global/documents/support/others/produc
ts/voice/CX300_HeadsetList_3810-48750-001_RevA.pdf .
• Make sure that the headset cord is attached correctly to the headset jack 
(not the handset jack) at the back of the phone, and any other connections 
needed by the headset are in place. A ‘click’ sound indicates that the cord 
is connected correctly.
If you still cannot hear a dial tone, refer to Using the Polycom CX300 Phone as 
an Audio Device on page 2-11.
The call does not connect.
• Dialing rules
Make sure that the phone number dialed complies with the dialing rules 
established for the organization.
• Locked computer
Check that the computer that the phone is connected to is not locked.
• Sleep mode
You cannot use the phone when the computer is in sleep mode.