meaning of error codes when sending fax

[gckTVfl]

Trying to send a fax on my officejet pro 6978 all-in-one printer. I have gotten error codes 350 and 339 on two attempts. What do these codes mean???

[Valsimot]

339:

The remote fax machine might be defective.

*Try to verify this by sending the same fax to other fax machines. If these transmissions are successful, notify the user of the remote machine.

*If the fax fails when sending to other machines, turn the unit off for ten seconds, turn it back on, and try sending again.

350:

The remote machine has failed to respond to a fax command from the local machine because the connection was interrupted. These errors can occur if the phone lines in the area are old or if noise is present (static on the phone line). Other reasons could be power outages and other power-related problems.

OR

The call waiting service can cause this error. The click, heard for an incoming call, is actually a momentary disconnect of the line.

OR
The remote user has pressed the Stop key while the reception was in progress.

OR

Under rare conditions, incompatibility between the two machines can cause the remote machine to simply abandon the call.

*Reattempt the fax reception at a different time when telephone line conditions have improved. Call the telephone provider if line conditions fail to improve.

*Disable the ECM. Errors might still occur, and might result in a degraded image quality on the received page. However, the ability to transmit the entire document will be improved.

*Try sending at a lower transmission speed.