In short
FaxTelecom transmits every page at the finest resolution the fax standard allows. The result is still a fax: black and white, and the sharper the more contrast your PDF has.
What a fax actually carries
Each page is turned into a black-and-white image, then sent in the high-resolution mode defined by the standard. Colour disappears: a pale fill may vanish, a dark one may turn solid black, and photos become a pattern of dots.
Stacking the odds in your favour
Go for dark text on a white background, a font of at least 10 points and generous margins. Steer clear of light-blue stamps, yellow highlighter and small grey print: those are the first things to become unreadable.
For a paper document, a flatbed scan or a smartphone's document mode gives a straight, high-contrast image. A photo taken at an angle under a lamp creates shadows that the fax will turn into black blotches.
The receiving machine matters too
The fax is printed again at the recipient's end, on their paper, with their toner or thermal roll. A worn-out machine can grey out or streak a page that left perfectly crisp.
Key points
- High-resolution, black-and-white transmission.
- Dark text, white background, 10 points minimum.
- A straight, high-contrast scan beats an angled photo.
- The final print also depends on the receiving machine.