A fax server is a system installed in a local area network (LAN) server that allows computer users whose computers are attached to the LAN to send and receive fax messages. Alternatively the term fax server is sometimes used to describe a program that enables a computer to send and receive fax messages, set of software running on a server computer which is equipped with one or more fax-capable modems (or dedicated fax boards) attached to telephone lines or, more recently, software modem emulators which use T.38 ("Fax over IP") technology to transmit the signal over an IP network. Its function is to accept documents from users, convert them into faxes, and transmit them, as well as to receive fax calls and either store the incoming documents or pass them on to users. Users may communicate with the server in several ways, through either a local network or the Internet. In a big organization with heavy fax traffic, the computer hosting the fax server may be dedicated to that function, in which case the computer itself may also be known as a fax server. User interfaces For outgoing faxes, several methods are available to the user: An e-mail message (with optional attachments) can be sent to a special e-mail address; the fax server monitoring that address converts all such messages into fax format and transmits them. The user can tell their computer to "print" a document using a "virtual printer" which, instead of producing a paper printout, sends the document to the fax server, which then transmits it. A web interface can be used, allowing files to be uploaded, and transmitted to the fax server for faxing. Special client software may be used. For incoming faxes, several user interfaces may be available: The user may be sent an e-mail message for each fax received, with the pages included as attachments, typically in either TIFF or PDF format. Incoming faxes may be stored in a dedicated file directory, which the user can monitor. A website may allow users to log in and check for received faxes. Special client software may be used. Advantages over paper fax machines Fax servers offer various advantages over traditional fax systems: Users can send and receive faxes without leaving their desks. Any printable computer file can be faxed, without having to first print the document on paper. Most of the problems on a fax server can