Hi ila_staff.
Support shared the following information:
G3 Mode is a mode for faxing that denotes the speed of transmission of the fax. G3 is a fairly standard operating mode for a printer to be configured to, and is the default for this model. Receive again is a feature that, when enabled, allows the printer to accept (or send) a “Receive again” command from the receiving fax machine if it requests it. This enables a “retransmit” if the receiving fax machine cannot completely interpret the message sent. In the case of your error report, the printer is simply indicating that during the fax, G3 mode was enabled (which is normal) and that a Receive Again request was made, due to the first not being completed properly.
As for the fax mistaking phone calls for faxes you may have line-related issues, and we advise that you contact support as it could be a fault of the device. 1-800-835-6100