Please confirm. Printer is a TR4720?
This model requires a conventional analog phone line to send faxes. People have tried to use VOIP phones to send faxes too, but if there is any pause or delay in packet transmission the fax will fail.
Here is an option. eFax. This service sends faxes using the internet, its also can receive faxes. Its basically email that uses a phone number as a destination. You can use your printer to scan what you want to send, and print what you receive. It is a subscription based service. Its not affiliated with Canon.
Bay Area - CA
~R5 C (188.8.131.52) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, +RF 1.4x TC, +Canon Control Ring, BG-R10~DxO PhotoLab Elite ~DaVinci Resolve ~Windows11 Pro ~ImageClass MF644Cdw ~Pixel 8 ~CarePaks Are Worth It
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.