Polycom error updating boot rom
Some other points which might be important to you are that the GXP-2000 boots up much faster than the 501 (50 seconds for the GXP-2000, three minutes for the 501) and the 501 is very sensitive to power failures during bootup.
If there is a power loss during the "Updating initial configuration..." phase, the config file that is written to the local flash will become corrupt and the the phone will be locked in an eternal boot cycle.
In the instructions below, TFTP is only really used to push out the firmware updates.
At time of this writing, Grandstream GXP-2000's are around 5, and Polycom 501's are around 0.
The Polycom 501's do have more and easier-to-get-to functionality than the GXP-2000's, and have a more professional look and feel (and a great speakerphone), but the most notable downsides of the 501 are its awful, obtuse and slow configuration interfaces.
Please see: Handbook Wiki Chapter 7 and read the Polycom phones section.
It REALLY goes in depth concerning all the files you're dealing with and also how to provision.