The law
A transmission report attests that an identified machine answered and acknowledged the document. An email only proves that a message left a server.
Understanding fax
What a fax really is, and why it is still here
Fax did not survive out of nostalgia. It survived because it produces a proof that neither email nor a web form can produce. Here is what happens on the line, and what it changes legally.
Short answer
A fax sends the image of a document from one machine to another over the telephone network. The sender gets a report stating that the receiving machine answered, accepted and acknowledged every page. That acknowledgement, not the content, is what gives it evidential weight.
What happens between the click and the report
Four operations separate the upload from the delivery receipt. None of them is visible on screen.
- 1
Upload
The PDF leaves the browser over an encrypted link. It is never printed: its vector content is read directly.
- 2
Rasterisation
Each page becomes a pure black-and-white image, no grey levels, at the definition fax machines expect.
- 3
Line negotiation
The gateway calls the remote machine and agrees on speed and error correction mode before a single page moves.
- 4
Transmission report
The remote machine acknowledges each page received. The report records the time, the duration and how many pages were accepted.
The facts, in six lines
| Transmission protocol | ITU-T T.30 / T.38 |
|---|---|
| Sending definition | 204 × 196 ppp |
| Accepted format and size | PDF — 10 Mo |
| Usual delivery time | ≈ 5 min |
| Destinations covered | 12 |
| Prefixes listed | 60 |
Why it has not disappeared
Three professional worlds still insist on it, and each has a different reason.
Healthcare
Exchanges between practitioners often travel outside open mail systems. A phone line stays a closed channel, with no intermediate storage.
Public administration
Court registries, benefit offices and prefectures keep written procedures that name the fax. Until the text is rewritten, the channel stays mandatory.
Frequently asked questions
- Does a fax hold legal weight?
- The transmission report is a starting point of proof: it establishes that an identified machine accepted the document at a given time. Its force then depends on the court's assessment and on the rules that apply to the case.
- Do I need a fax machine to send a fax?
- No. An online gateway replaces the hardware: it converts the file and places the call on your behalf. Only the receiving end still has to be a fax machine, physical or virtual.
- Does fax still work over fibre?
- An analogue machine plugged into a fibre router often fails, because voice travels in packets. Going through an online gateway avoids the obstacle, since the call starts from the operator network rather than the home.
Send a fax now
The form fits on one page: a PDF, a recipient and a return address. No account, no card.
Open the form