fax class

For the personal computer( PC) controlled telecopying (fax) according to fax group 3, the International Telecommunication Union( ITU) has developed command sets which are summarized in the fax classes.

These command sets use the AT commands to smoothly control communications between personal computers, fax cards, and fax modems. The ITU has defined three fax classes, 1, 2 and 2.0.

In the oldest fax standard, Fax Class 1, the personal computer controls the communication, which imposes a corresponding processor load. Fax class 2, the precursor to fax class 2.0, was supported by some companies before it was adopted and differs from fax class 2.0, which was adopted later. Fax Class 2.0 has error correction and compression and an extensive command set. In this fax class, the fax modem handles various processing steps.