Fax Modem Classes: What Are They?

What Class 1, Class 1.0, and Class 2 actually controlled on a fax modem, and why cloud faxing doesn't use any of them.

Door

Sarah Mitchell

Gepubliceerd op

September 9, 2026

Laatst bijgewerkt op

September 11, 2026

Fax modem classes (Class 1, Class 1.0, and Class 2 or 2.0) define how much of the fax transmission process a computer's software handles versus the modem's own hardware.
Class 1 modems hand most of the underlying protocol work to software; Class 2 modems handle more of it internally.
Fax.Plus runs entirely in the cloud, so no local fax modem or modem class setting is involved on the sender's end.

What Are Fax Modem Classes?

A fax modem class describes how much of the work of sending a fax, negotiating the connection, formatting data, handling errors, a computer's fax software does itself versus how much the modem's own hardware and firmware handle internally. The classes were defined so fax software from different vendors could reliably talk to modems from different manufacturers.

Class 1 vs. Class 1.0 vs. Class 2

Class 1: the most basic, performs only low-level signaling and leaves almost all of the transmission logic to the computer's software.
Class 1.0: a later revision of that same approach that adds support for faster V.34 modulation.
Class 2 (and its revised version, 2.0): shifts more of that protocol handling into the modem's own firmware, reducing the load on the host computer but requiring the software to support that modem's specific command set.

Determining which class a modem supports also determines which fax compression coding method it can offload versus leave to software.

Why This Doesn't Apply to Cloud Faxing

Fax.Plus has no local fax modem, and by extension no modem class, anywhere in the process. Documents are sent from a browser, app, or email, and the transmission itself happens on Fax.Plus's own infrastructure rather than a modem installed in the sender's computer. There is nothing to configure, because there's no modem hardware on the user's end to configure in the first place.

A Common Case: Configuring Legacy Fax Software

An IT technician setting up older fax software on an office PC checks whether the installed modem supports Class 1 or Class 2 commands before finishing the configuration, since the fax driver needs to know which one it's talking to.

Veelgestelde vragen

What is the difference between fax Class 1 and Class 2?

A Class 1 fax modem hands most of the fax protocol work to the computer's software, while a Class 2 modem handles more of that negotiation internally, in its own firmware. Class 2 generally puts less load on the connected computer.

Does Fax.Plus use a fax modem class?

No. Fax.Plus runs entirely in the cloud with no local fax modem involved on the sender's end. Modem classes only apply to hardware-based fax setups that rely on a physical modem to connect.

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