If the default Polycom password of 456 does not work, or if someone has changed the admin password on the phone, please do the following:
Find and write down the MAC address (serial number) of the phone you want to reset. It should be twelve characters, and look something like '0004F2ABCDEF'. If you can't read the back label, you can find the MAC address by pressing Menu, Status, Network, Ethernet.
Power down the phone.
Power up the phone.
While powering up the phone (you have about 6-8 seconds to complete this step):
For SoundPoint IP 320, 321, 330. 331, 335, 430, and 450 press and hold the 1, 3, 5, and 7 on the dial pad at the same time.
For SoundPoint IP 301, 501, 550, 600, 601, and 650 press and hold the 4, 6, 8, * on the dial pad at the same time.
After holding down the numbers for few second, you will be prompted to enter the admin password. Enter the MAC address of the phone. No colons and the alpha characters must be entered as lowercase letters