Fax Overview

Yeastar P-Series Cloud Edition allows you to connect your fax machine to PBX system. Then you can send or receive faxes on a fax machine, and receive faxes by email. This topic describes how fax works with Yeastar P-Series Cloud Edition, and introduces fax to email, fax detection, and Fax over VoIP settings.

T.38 Fax

T.38 is a protocol that enables fax over the Internet and is supported on Yeastar P-Series Cloud Edition. T.38 utilizes Voice over IP (VoIP) to send a fax. This process is known as virtual fax or FoIP (Fax over IP).

The diagram below explains how T.38 Fax works:

  1. A fax machine sends a fax through a T.38 compatible gateway, which acts as an emitting server.
  2. The emitting server partitions data from the fax into an image that can be encoded and sent over the Internet in real time, then sends the T.38 data stream to another T.38 compatible server, such as a PBX, which acts as a receiving server.
  3. The receiving server converts the T.38 data stream to analog signal, and sends to the terminal fax machine.

Fax to email

Faxes traditionally are sent directly to a fax machine; the recipient receives a printed copy. Yeastar P-Series Cloud Edition provides fax to email feature that allows you to receive faxes as PDF by email.

The benefits of fax to email:
  • Keep your faxes private without paper trail.
  • Access faxes in real-time from anywhere.
  • No need to pay for expensive hardware, printer paper, ongoing maintenance or a dedicated fax line.

Fax detection

Fax detection is used to detect automatically whether an incoming call is voice or fax. It is useful when you have fax call and voice call on the same line.

  • If the PBX detects a fax signal, the PBX immediately routes the call to the designated fax destination.
  • If the PBX does not detect a fax signal, the PBX handles the call as a regular voice call.

Fax over IP (FoIP) settings

The following settings are available when you want to improve the Fax transmission over VoIP network.
  • T.38 Support: Enable or disable T.38 protocol for extension and trunk according to your needs.
  • T.38 Max BitRate: The maximum bit rate of the fax transmission.

    The default value is 14400.

  • No T.38 Attributes in re-INVITE SDP: Whether to contain T.38 attributes in SDP re-invite packet.
  • Error Correction Mode: Error Correction Mode (ECM) is an optional transmission mode. ECM automatically detects and corrects errors in the fax transmission process that are sometimes caused by telephone line noise.