Resetting the configuration on a Polycom VVX 300
September 24, 2014
Power on the VVX, wait for the Starting Application dialog and press Cancel to stop it. The Welcome dialog will count down from 7 and press 1, 3, and 5 simultaneously and you'll see a password prompt.
Enter the MAC address, lower case. For letters, select the a->1A mode and press the key the amount of times the letter is. So for f you would press 3 three times. Go slowly as there's no backspace. If you get it wrong press the 1, 3, 5 combo again to try again.
Once you get it right the phone will reboot and it will be reset to the default 456 password.