The invention provides a network fax converter comprising an exchanger PBX and a Fax / Voice modem, wherein, interfaces of the exchanger PBX are respectively connected with the Fax / Voice modem, an exterior line of a telephone and an internal 
telephone line, the other end of the modem is connected with a computer which is connected with an Internet; and a 
file format conversion module, an e-
mail address generation module, an e-mail generation module, a sending module and a 
configuration management module are arranged in the computer. The invention further provides a central network fax 
service system which uses the network fax converter, and the 
system also comprises a fax 
machine, a special mail 
server, a SMS 
server, and the like. The invention aims at providing the network fax converter and the central network fax 
service system which can send a fax to all the people who own 
mobile phone numbers around the world by utilizing a standard fax 
machine without the need of local access number, the user who receives the fax does not need to register in advance, the fax can be received around the world for free, and the sending or the receiving of the fax can be fully electronic.