When sending a fax, you may receive a Delivery Report stating "Result: Communication Error"
Comm Error means the sending service was unable to reliably send the fax to the receiving fax machine.

Communication errors can occur for a handful of reasons. The common ones are:

• Poor line quality (line is crackly or has heavy static so the fax tones are dropped or muffled)
  Fixing this issue often requires TNZ's intervention; contact Support for details
  
  
• Dense image (lots of heavy black means more beep tones which means faxes are more difficult to send)
  Check out our Best Practices guide for details
  
  
• An incompatible receiving fax machine
  This issue is rare and often requires TNZ's intervention; contact Support for details

Due to one of the reasons above, the sending fax machine will determine whether the call should proceed. The receiving fax machine is designed to simply sit and listen for instructions.

howto, how to