I have an HP 8500A printer/scanner/fax. Everything works but the fax. I can receive but I can't fax out. I get error 348, 321 & 358.

Hello and Welcome to FixYa!

Sir/Ma'am these error are basically due the Communication error of Receiving/Remote Machines. But each error shows different meaning.If during fax you receive the Error 348 then it may be because of several reasons like:-

1. 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,Other reasons can include power outages and other power-related problems.
   
2. When The call-waiting service can cause this error or the remote user pressed the Stop key while the reception was in progress.
   

• 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.
• Try sending at a lower transmission speed.
  

1. There was a communication error with the receiving fax machine due to poor telephone line conditions.

• The remote user pressed the Stop key, causing the session to be terminated.
  
• The remote machine encountered a system problem such as no paper or a paper jam. This prevented the fax from receiving any more pages, and caused it to terminate the session prematurely.
  
• 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 machine encountered an incompatible feature causing it to terminate the session.