When I first got my HP Officejet Pro 8500A I had no problem faxing. Now I get an error 350 code. Why? How can I fix this problem

HP's description of this error code is as follows

Definitions

• The remote machine 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 to be faxed are old or there is noise (static on the phone line). Other reasons can include power outages and other power-related problems.
• The call-waiting service can cause this error. The click, heard for an incoming call, is actually a momentary disconnect of the line.
• The remote user pressed the Stop key while the reception was in progress.
• Under rare conditions, incompatibility between the two machines might cause the remote machine to abandon the call.

• Retry the fax reception at a different time when telephone line conditions have improved. Call the telephone provider if line conditions fail to improve.
• Disable ECM. Errors might still occur, and might result in a degraded image quality on the received page. However, the ability to send the entire document will be improved. Click here for instructions on enabling and disabling ECM (c00060802) (in English).
• Try sending at a lower transmission speed.