Outbound Fax With An ATA

TL;DR

Outbound faxing with an ATA can be challenging due to the nature of VoIP connections, where packets may be discarded or delayed. To improve faxing over VoIP, it is recommended to slow down the transmission speed, set the BAUD rate to 9600 bps or lower, and disable error correction mode. These settings can help make faxing over VoIP more consistent, but may not resolve all issues. Alternative options, such as the vFAX service or eFax, are available for reliable faxing.

We offer vFAX which is a special fax ATA that faxes over HTTPS, solving the issues found with using a traditional ATA. Contact support for more details.

In the world of VoIP, voice is first converted into packets and then they are sent over the connections that make up our our vast Internet. They may take slightly different times to arrive at their destination. In doing so some packets may be discarded, but the end result is that the receiving VoIP device has enough packets to make a clear and understandable voice conversation. However, fax machines listen for specific tones that then are converted into the fax data.

We suggest these settings on a fax machine for faxing over VoIP:

Slow down the transmission speed.
Set the BAUD rate of the fax machine to 9600 bps or even lower (7200 bps would be the next slower setting).
Turn off or disable ECM (error correction mode), a setting, usually defaulted on, that many fax machines have.

Slowing the transmission rate down and allowing the machine to continue receiving the transmission even though a few bits of data were lost, then faxing over VoIP can become more consistent. Our suggestions in many cases can resolve issues that prevent faxing over a VoIP connection, but not in all cases. If after trying and making all the VoIP fax changes we suggest you still cannot fax over your connection then try using our eFax service (which is free with most accounts).