Black fax to harass large institutions or government departments, to retaliate against the senders of junk faxes, or merely as simple pranks. The basic principle of a black fax can be extended to form a "black fax attack." In this case, one or more sheets are fed halfway through the sender's fax machine and taped end to end, forming an endless loop that cycles through the machine. Not only can solid black be used, but also images which will repeat endlessly on the receiver's machine until its toner runs out. The introduction of computer-based facsimile systems (combined with integrated document imaging solutions)
Internet fax usually another fax machine, which then transforms these pulses into images, and prints them on paper. The traditional method requires a phone line, and only one fax can be sent or received at a time. The phone connection must not be a packet-based system in which delays can occur—a VoIP connection will not work well without special precautions (T.38-compliant equipment at both ends). Internet fax achieves a dramatic reduction in communication costs especially when long faxes are frequently exchanged with overseas or distant offices. Since there is no telephone connection charge when sending a fax over the Internet, the cost