Fax Tone

Fax tone refers to the specific fax sound signal sequence used by fax machines to establish a connection and begin transmitting fax data over a telephone line. It is the recognizable high-pitched sound you hear when a fax machine answers a call or when two fax devices are negotiating how to communicate.

Fax tones are part of the technical handshake process that allows two fax devices (or a fax device and an online fax service like Notifyre) to confirm compatibility, transmission speed, and error correction settings before sending document data.

Fax tone detection is still relevant today because many systems, including cloud fax platforms, must interpret or emulate these signals to communicate successfully with traditional fax machines and carrier networks.

How Machine Fax Tone Works

Fax tones are exchanged during the early stages of a fax call to confirm that both devices are fax capable and ready to communicate. During this setup process, fax machines first detect each other using identification tones, then perform a handshake to agree on transmission settings before sending the document data. These steps help ensure reliable delivery and reduce the risk of transmission errors.

Fax Tone Detection

When a fax machine answers a call, it typically emits an identification tone. This tone signals that the receiving device is ready to receive a fax transmission.

If the calling device detects this tone, it proceeds with the fax communication process. If no fax tone is detected, the call may be treated as a voice call instead.

Fax Handshake

When a fax machine answers a call, it typically emits an identification tone. This tone signals that the receiving device is ready to receive a fax transmission.

If the calling device detects this tone, it proceeds with the fax handshake process. If no fax tone is detected, the call may be treated as a voice call instead. 

Fax Machine Handshake

After tone detection, both devices exchange additional signals to determine:

• Supported fax standards

• Fax transmission speed

• Error correction capabilities

• Compression methods

This ensures both sides can transmit data reliably without corruption or loss. 

Fax Data Transmission

Once negotiation is complete, the fax document is transmitted as encoded data over the fax line or through digital carrier infrastructure.

In modern online fax services like Notifyre, the platform may simulate or interpret fax tones digitally while still maintaining compatibility with traditional fax machines.