What Is a Virtual Fax?

What is a virtual fax

Fax (short for Facsimile, meaning "exact copy") is a way to send a printed page over a phone line: one machine scans the page and turns it into sounds, and the machine on the other end translates the sounds back into a page and prints it. A virtual fax does the same thing without the machine. The PBX receives and sends the fax, and you work with files: a document on your computer goes out as a fax, and an incoming fax lands in your email.

For the person on the other end — a government office, an HMO or a longtime supplier — nothing has changed. They send a fax to your number as usual, or receive a fax from you on their machine as usual. The whole difference is on your side: no paper, no ink, no machine taking up space, and no separate phone line just for it.

A brief history of fax

Fax is much older than it seems. The first patent for transmitting an image over electrical wires was registered by the Scottish inventor Alexander Bain in 1843, before the telephone was even invented. In the 1860s, the first commercial service operated in France, Giovanni Caselli's "pantelegraph," which transmitted documents and signatures between cities.

For decades, fax was used mainly by the press, police and weather services, to transmit pictures and maps. The revolution came when the machines became cheap and small, and especially when a single international standard ("Group 3," in the early 1980s) allowed any machine to talk to any other machine. In the 1980s and 1990s, fax was in every office, and "send it to me by fax" was the usual way to transmit a contract, an order or a prescription.

Email and scanners pushed fax aside, but didn't make it disappear. And as telephony moved to the internet (VoIP), fax moved to the network too, and that is how the virtual fax was born.

Why organizations still use fax

It sounds outdated, but there are real reasons:

• Bodies that work by fax — some government offices, local authorities, hospitals, HMOs, courts and longtime suppliers still request and send documents by fax.
• Delivery confirmation — a fax machine produces a report that the document was received on the other end, on a specific date and time. Some organizations treat this as proof that the document was sent.
• Simplicity — no password, no full mailbox, and no message that fell into spam. You dial a number and the page arrives.
• Habit and procedures — in many institutions the procedure is simply written that way, and no one will change it for you.

What this means for an office: even if you almost never use fax, it's worth having a fax number. It's usually on exactly the day someone says, "Fax it to us by noon."

How it works behind the scenes

Incoming fax: someone sends a fax to your number. The call reaches the PBX, and the PBX "answers" like a fax machine: it receives the sounds, builds the pages from them, saves them as a file and sends it to the email you set up. You can open the fax on your mobile phone, forward it, or print it only if needed.

Outgoing fax: you choose a file — a PDF, a Word document or a photo of a page — and a destination number. The system converts the file to fax pages of the right size and quality, dials the destination, and "talks" to the fax machine on the other end exactly like a real machine.

Why not simply connect a regular fax machine to an internet line? You can, but it's less reliable. VoIP calls are compressed to save bandwidth (see codec), and the fax signal is sensitive to compression and packet loss — a long fax may be cut off in the middle. That's why a special standard for sending fax over a network was created in the VoIP world, and why a virtual fax, where the PBX itself handles the fax, tends to work more smoothly than an old machine behind an adapter.

Virtual fax vs. a fax machine

There are limitations too: a virtual fax won't scan a page you received on paper — for that you need a scanner or a phone with a camera, and then you send the image. And anyone who must have an "original" stamp on paper won't be helped by a fax of any kind.

Real-life examples

• An accounting firm in Bnei Brak — receives approvals from the tax authorities and National Insurance by fax. The faxes arrive in the office's shared email, and from there they're saved straight to the client's folder, with no need to scan again.
• A yeshiva with a dormitory — the secretary's office sends students' forms to the HMO. Instead of looking for a machine that works, they send the PDF file from the computer.
• A nonprofit that works from several locations — the coordinator works from home three days a week, and still sees every incoming fax, because it arrives in her email.

Tips for sending a fax that arrives well

• Contrast — fax is mostly black and white. Light gray text or a colored background may come out blurry.
• Straight photo — if you send a photo of a page, shoot from directly above, in good light, with no shadow from your hand.
• Uniform size — an A4 document comes out best. Very long or very narrow pages will be resized.
• Correct number — make sure it's a fax number and not a regular phone number. If a person answers, the fax will fail.
• Email for faxes — it's a good idea to set up a shared mailbox for incoming faxes (for example, the secretary's office), not the private mailbox of one employee.

Sending step by step: from a PDF or Word file

Suppose a yeshiva secretary needs to send an HMO a three-page form, saved as a Word file. This is how it looks from start to confirmation:

1. Prepare the file. Check that all the pages are there and that the text is black on white. If there's a signature or a stamp, scan or photograph it and paste it into the document. Save.
2. Open the fax screen in the control panel. Choose the file from your computer — PDF, Word or an image. The system converts it into black-and-white fax pages, A4 size.
3. Enter the destination number. The other party's fax number, as you would dial it from a phone. It's best to copy it from the recipient's document rather than from memory.
4. Send. The PBX dials, waits for the sound of the fax machine on the other end, and transmits the pages. Three pages usually take one to three minutes, depending on the recipient's machine.
5. Check the status. Sent successfully — you're done. Failed — you can see why: busy, no answer, or a person answered instead of a machine. Try again after a few minutes.

A tip for Word: before sending, save a copy as a PDF and open it. What you see there is what will be sent. That way you catch a table that broke across two pages or a font that wasn't embedded. And if the document is in color, imagine it in black and white: light orange on white comes out almost invisible.

Receiving by email: what happens and what to do

An incoming fax arrives as an email message with an attachment — usually a PDF — and the body of the message shows the number it was sent from and the number of pages. From there it's an email like any other: open it on your mobile on the go, forward it to the accountant, save it in the client's folder.

A few habits that turn this into an archive rather than a pile:

• Shared mailbox — faxes arrive at an address like the office's fax@, which several people can see. An urgent fax doesn't get stuck in the mailbox of someone who is on vacation.
• Sorting rule — in your email program, set every message from the fax address to go into a folder called "Incoming Faxes."
• File name — when saving, rename the file to something searchable: "Tax Deduction Approval — Levi — 2026-03."
• Who handles it — mark the email as "handled" or pass it to whoever is responsible, so a fax isn't handled twice or never.

And if you want paper too, an incoming fax can also go to a fax machine connected to the PBX, so it's printed immediately and also saved in email. That way the secretary's office gets a page in hand, and the archive stays digital.

Why fax through the PBX beats a machine on an old line

• No busy signal. A machine on one line receives one fax at a time. On the PBX, several faxes can come in at once, and each one reaches your email.
• There's a log. Every fax, incoming or outgoing, appears with a date, number and status. On an old machine, it's a report page that gets thrown away.
• No paper problems. The toner runs out, paper jams, the machine is turned off at night — and the fax doesn't arrive. By email, it always arrives.
• No separate line. The fax number is just another number on the PBX, with no payment for an analog line that exists only for it.
• Send from anywhere. From home, from your mobile, from another branch — the same screen.

An old machine connected to the PBX through an adapter stays useful as a printing and scanning station, but it's no longer the only dependency: if it's off, email still receives.

Moving your existing fax line: a transition plan

1. Mapping. Who sends you faxes? Authorities, suppliers, customers. Write down the fax number that appears on your letterhead, on the website and on forms.
2. Number. Port your existing fax number to the PBX (number porting), or get a new number if the old one doesn't matter.
3. Destination. Decide where an incoming fax goes: email, a machine, or both.
4. Parallel. For the first two weeks, leave the old machine connected through an adapter, so that no fax is lost while you get used to the new setup.
5. Test. Send a test fax from the PBX to an outside machine and back, and check that the pages are complete.
6. Update. If the number changed, update your letterhead, email signature and website.

When a fax doesn't go through: symptom, cause, fix