When using Epson Device Admin, you can set the IP fax settings on multiple printers as a batch.
For details, see the manual or help for Epson Device Admin.
Software for Managing Devices on the Network (Epson Device Admin)
Operation Flow of Epson Device Admin
Enabling Sending and Receiving IP Faxes on an Intranet (Intranet Settings) <Epson Device Admin>
Enabling Sending and Receiving IP Faxes Using G3 Fax-compatible Devices (Through a VoIP Gateway) <Epson Device Admin>
Setting Items for IP-FAX Settings > VoIP Gateway Settings <Epson Device Admin>
Registering a VoIP Gateway <Epson Device Admin>
Priority Settings for VoIP Gateway <Epson Device Admin>