Solutions
If you do not know the performance of the sender’s fax machine, set the following before sending a fax.
Select Fax > Menu > Scan Settings and then make the Resolution setting to set the highest quality image.
Select Fax > Menu > Fax Send Settings and then enable Direct Send.
Note that if you set Resolution to Photo but you send the fax without enabling Direct Send, the fax may be sent at a lower resolution.
Solutions
Select More > Settings > Fax Settings > Basic Settings and enable the ECM setting on the printer's control panel. This may clear errors that occur due to connection problems. Note that the speed of sending and receiving faxes may be slower than when ECM is disabled.