When using EPM to configure Yealink phones the default action for pressing a DSS key on a transfer call is a blind transfer. All my clients prefer attended transfers, so instead of having to deploy the config from freepbx epm to the phone, then logging into the phone gui and changing it (features > transfer > transfer mode vis dss key > attended transfer), simply edit the basefile parameter: transfer.dsskey_deal_type = 2 & change the value to 1. Then when you provision your phones, they will get the right setting from the fpbx epm config file, no need to login to each phone manually.
Correct. That is the point of the base file edit. To allow you to change details.