I assume it is in /tftpboot but, no idea if a username/password exist. Second, I did find some config files in this directory, that do not match my extension.
For example, I have my polycoms extension set as 200 though the Polycom ip500 phone provision module set in Freepbx.
In /tftp there is :
licenses sip_213.cfg
0004f201f2c8_reg.cfg logs SoundPointIPLocalization
config_bkup overrides SoundPointIPWelcome.wav
contacts phone1_213.cfg
languages server_213.cfg
I changed the ip500 boot directory from ftp to tftp with no user/password and it had provision errors.