Internet fax machines. This has limited the standard's use, though a system for looking up a fax's email address based on its phone number is under development. To work with existing fax machines, all iFax machines support standard faxing (requiring a regular phone line). Alternatively, an iFax can be used in conjunction with a fax gateway. Internet fax Internet fax, e-fax, or online fax is the use of the internet and internet protocols to send a fax (facsimile), rather than using a standard telephone connection and a fax machine. A distinguishing feature of Internet fax, compared to other Internet communications such as
Internet fax Not all fax equipment claiming T.38 compliance works reliably. In particular communicating with older fax machines is problematic. As with regular faxes, only one fax can be sent or received at a time. While the needs of computer-to-fax communications are well covered, the simplicity of quickly faxing a handwritten document combined with the advantages of email are not. "iFax" (T.37) was designed for fax machines to directly communicate via email. Faxes are sent as email attachments in a TIFF-F format. A new fax machine (supporting iFax/T.37) is required, as well as a known email address for the sending and receiving