For sending an occasional fax, many business customers find Fax-over-Internet services to be cost-effective and adequate for their needs. However, faxing over the internet has known limitations. RingCentral uses the T.38 standard for faxing and adheres to the FCC guidelines regarding its use. This standard is interpreted differently by the various carriers and service providers on the public telephone and internet networks. Given this, the T.38 standard cannot be guaranteed on all end to end connections. As with any new service, it is best to test speed, quality, and reliability in advance of adoption.
If your business is heavily dependent on regularly faxing large, multi-page documents, we recommend that you maintain an analog landline and a traditional fax machine for reliable and consistent performance.
Partially Received Faxes
You might receive partial faxes, such as incomplete pages or pages are cut off. Faxing has known limitations when implemented as a Fax-over-IP service. These limitations are technology-based and industry-wide.
Several VoIP companies, including RingCentral, use the T.38 standard for sending faxes over the Internet. Although the standard promises better reliability, that standard is still open to interpretation by various providers and cannot be maintained on an end-to-end basis.
Follow the steps below to help RingCentral Support isolate where the issue is coming from.
1. Check your Received Fax History via the Call Log section on your RingCentral Online account
• This is to determine if the partial faxes are being received from a single number only. See Filtering Call Log to learn how.
• If you have access to the sending machine (the machine from where you received the partial fax),
• lower the baud rate to 9600 and
• turn off Error Correction Mode and/or Overseas Mode.
NOTE: Steps may depend on the Fax Machine model.
2. If the faxes are being forwarded to your RingCentral Fax Number from a different carrier, have the sender send a fax message directly to your RingCentral Fax Number.
3. If issue is happening on multiple sending numbers, gather samples that is from within the last 24 hours for possible carrier escalation. Please Contact RingCentral Support for assistance.
Partially Sent Faxes
• Ensure that the attached files are supported. For more information, go to Supported File Attachments for Faxes.
• The file name of attached files should not include ampersands (e.g. &) or other special characters.
• Ensure that the attachment does not exceed 200 pages.
• Ensure that the combined size of all attachments do not exceed 20 MB.
Please check below if you're experiencing other issues.