Do I need to use a filter if I fax over a VoIP (Voice over Internet Protocol) line?
No, a filter is only required if you use a DSL connection.
Fax machines are designed to work over standard analog phone lines. Epson does not guarantee that fax transmission will work over VoIP phone lines (including cable systems such as Cox, Charter, Spectrum, Comcast, FiOS, magicJack, and Vonage).
Internet traffic can interfere with faxing because VoIP communicates through the Internet and not through standard analog phone lines. The data sent over the Internet for a fax is digitized into packets, and this process can cause data loss.
You can try slowing the transmission speed of the fax by setting ECM on the product to Off and selecting a slower Fax Speed. If this does not help, contact your VoIP service provider for help.
Note: If you set ECM to Off, you will not be able to send or receive a color fax.
For more information, please contact your phone service provider.