Faxing depends on the machine at the other end answering and cooperating, so the occasional failure is normal. The good news: most failures come from a short list of causes, and each has a simple fix. This guide walks through them in plain language.
First, check the status
Open Fax → Inbox and look at your Outbox. A failed fax is marked Failed, and a fax that is still retrying shows Retrying. We automatically retry a fax that hits a busy or dropped line, so give it a few minutes before assuming it failed. If it does fail, use the Retry button to try again without re-uploading.
Common causes and fixes
The line was busy
The recipient's fax machine was on another call. This is the most common cause and usually resolves itself — we retry automatically. If it keeps failing, wait and try again later, when the line is likely free.
Wrong number, or not a fax line
Double-check the number you entered. Make sure it is the recipient's fax number, not their voice line. A voice number will never answer with a fax tone, so the fax cannot go through. If you can, call the number first — you should hear a fax tone.
The receiving machine had trouble
Some fax machines are old, low on paper or toner, or briefly offline. If one recipient consistently fails while others work, the problem is almost certainly on their end. Ask them to confirm the machine is on and ready, then resend.
The document was too long or too large
Very large files and very long documents can time out mid-transmission. If a big fax keeps failing:
- Split it into smaller batches of pages and send them separately.
- Keep each file under 50 MB. When uploading in the portal, use a PDF or TIFF. When sending by email, you can also attach Word, Excel, PowerPoint, and image files — up to 10 attachments and 50 MB total — and we convert them for you.
The document was hard to read
Faint text, heavy color images, or unusual page sizes can cause errors. For best results:
- Use clean, high-contrast black-and-white documents.
- Stick to standard letter or A4 page sizes.
- Try a higher Resolution (Fine or Super Fine) for small print or detailed forms.
Faxes you are not receiving
If people say they faxed you but nothing arrived:
- Check the correct fax mailbox under Fax → Inbox and Fax → Mailboxes.
- If you use email delivery, check your email spam or junk folder.
- Confirm the sender used your correct fax number.
- Ask the sender whether their machine reported success.
When to contact support
If faxes to a specific recipient fail again and again, gather a few details and open a support ticket:
- The recipient's fax number
- The status or error shown in your Outbox
- The document you were sending
- The dates and times of the failed attempts
That information helps us pinpoint whether the issue is the destination machine or something we can fix on our side.
Related articles
- Sending a fax from the portal
- Send a fax by email (email-to-fax)
- Receiving faxes and fax mailboxes