You don't need anything to get your phones to register
The 46xxsettings.txt file is generated automatically when it it requested, so there is no need to create one and upload it.
browse to
address of IP Office>/46xxsettings.txt
If you have some parameters that need to be different than default, browse to
address of IP Office>/46xxspecials.txt
Modify that text, (remove the first line that says it was autogenerated), save as 46xxspecials,txt, upload to the Primary folder.
The phone will ask for the settings file, the autogenerated settings file will include get 35xxspecials.tx as the last line, now the phone will pull the specials file you created, and pick up its additional settings.