I also don't go into pushing out configurations from XML files on a TFTP server, but it may be the way to go if you're doing more than one phone.In the instructions below, TFTP is only really used to push out the firmware updates.
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.
Asterisk Bulk Provisioning Polycom Phones tutorial Set up and start up your TFTP server and make sure the files from the Boot ROM and the SIP archives are un ZIPped and in the root TFTP directory.
By default, the root TFTP directory is tftpboot, but this may be different on your machine if someone has changed it.
When it powers on, it will give you a menu for a few seconds. Otherwise, change it to Disabled and put in the IP/subnet mask/DNS/domain name/gateway info manually.
Press the middle SETUP soft button to interrupt the boot. Use the arrow keys, Sel and Del buttons to make edits.
Instead of setting these phones up by hand they should ALL be setup via files on the the FTP server.
At the end of the day, an administrator really shouldn't even have to even touch the phone other than setting up the FTP server, login and password.
About the Polycom 501If you're reading this to see how good certain phones are with Asterisk, let me tell you that the Polycom 501 has excellent features, but is a pain to configure and very tempermental.
I've used Soyo phones (they're the worst all around), ip Dialog phones (they're only a little better) and Grandstream's GXP-2000.
(By the way, I tried leaving out some of the XML config files, and Weird Things Happened(tm).