传真是人们熟悉的一种图像通信业务，是办公自动化不可缺少的工具。尽管传真机按照用途和工作特点，可以分为文件传真机、照片传真机、报纸传真机以及云图气象传真机等，但以往各类传真机都是采取“借鸡下蛋”的方式，利用公用电话网进行传递，而且像打电话那样采取电路交换方 Fax is a familiar image communications business, is an indispensable tool for office automation. Although the facsimile machines can be divided into file facsimile machine, photo facsimile machine, newspaper facsimile machine and cloud meteorological facsimile machine according to the purpose and working characteristics, all kinds of facsimile machines in the past adopt the method of “laying eggs with eggs” and make use of public telephone Network for delivery, and as circuit-switched on the phone