Knowledge Base

Connecting a Fax Machine

A standard phone splitter (duplex phone splitter) can be used to connect both a phone and a fax machine or DVR to the PHONE port of the Ooma Telo. If you're using an Ooma Hub, we recommend that you connect your fax machine to the Ooma Hub and NOT the Ooma Scout.

Alternatively, you may choose to dedicate the PHONE port usage to only connect a fax machine (or a DVR, for example) and use the cordless Ooma Telo Handsets as phones.

Be sure that the auto-answer mode on the fax is turned off or if turned on the delay to auto-answer should be set very high in order for the Ooma Voicemail to handle unanswered voice calls.

Sending and Receiving Faxes

Dial the prefix *99 before you dial an outgoing Fax call. Please note that you may need to insert a pause or two in the dialing sequence after entering the *99 prefix and before entering the Fax number.

If you are still unable to send or receive a Fax, try the following additional steps:

1. Disable “ECM” (i.e., “Error Correction Mode”) on your Fax machine.
   
2. Decrease the transmission or baud rate.
   
3. Reduce the number of pages that are sent per fax.
   
4. Decrease the desired image quality of the fax.
   
5. Discontinue any large file downloads (for receiving faxes) or uploads (for sending faxes).
   

If your fax machine is set to receive faxes, we recommend setting the fax machine in "manual" mode so that it does not automatically pick up calls and interfere with Ooma's voice mail receiving calls.

You may need to refer to your Fax manufacturer user manual or web site for information on how to perform some of the steps mentioned above.

Fax Mode (required for Ooma Telo)

If you plan on receiving faxes on your Ooma Telo, you must enable "Fax Mode" on the Preferences->Phone Numbers page in My Ooma. This enables the Ooma Telo to run in an optimized mode for receiving faxes.

No special settings are needed for receiving faxes on the Ooma Hub.

Note: In fax mode, your calls are sent and received using a different audio processing algorithm. In certain conditions, this can cause the quality of your voice calls to diminish. As a result, we recommend that you only enable fax mode only if you're actively receiving faxes.

Background Information: Voice over IP (VoIP) and Fax Machines

A common question comes up - why are faxes not guaranteed reliable 100% of the time when using VoIP technology?  The reason has to do with how faxing was originally developed. The faxing protocol was originally developed for regular landlines.  Unlike IP networks which route VoIP, landlines are fairly lossless.  This makes faxes less resilient to dropped packets and delay inherently present in all IP networks today.  Ooma is currently looking into new ways to improve the reliability of faxing with the Ooma system, including use of the T.38 FoIP protcol.