What Is eFax — Explained Simply

By David Thompson · Published December 5, 2025 · Updated September 18, 2026 · 7 min read

You need to send a fax, but you don't have a fax machine. Someone mentions "eFax" — but what is eFax, exactly? Is it a service? A technology? And do you actually need it?

eFax is simply faxing over the internet. No machine, no phone line, no paper. You send a file from your phone or computer; it arrives at the recipient's fax machine (or inbox) just like any other fax. This article explains how it works, when to use it, and whether eFax.com specifically is worth paying for.

What Is eFax?

eFax — short for electronic fax — is the umbrella term for any fax service that uses the internet instead of a traditional analog phone line. You may also hear it called internet fax, online fax, or digital fax. They all mean the same thing: faxing without hardware.

You need two things to use eFax:

1. A virtual fax number — a real phone number assigned to you by the service
2. An internet connection — your phone, laptop, or tablet is the "fax machine"

The virtual fax number is what makes it compatible with traditional fax machines. The person on the other end dials a normal number; they never know it's routed through the internet.

How Does eFax Work?

The process is straightforward, even if the technology behind it isn't.

Sending a fax via eFax:

1. Open the app or web portal and upload your document (PDF, Word, image, etc.)
2. Enter the recipient's fax number
3. The eFax server converts your file to a fax-compatible format
4. It transmits the signal over the internet to the recipient's fax machine or virtual number
5. You receive a delivery confirmation

Receiving a fax via eFax:

1. Someone dials your virtual fax number from any fax machine
2. The eFax server intercepts the analog signal
3. It converts the fax to a PDF file
4. The PDF lands in your email inbox or online portal

The entire chain — document → internet → fax signal → PDF — happens in seconds. From the recipient's perspective, it looks exactly like any other fax.

Under the hood, the service encodes your file to the same fax standards a physical machine uses (T.30, or T.38 for fax over IP), carries it as encrypted data to its own servers, and bridges from there onto the public telephone network (PSTN) for the last leg to the destination number. Because no single phone line is involved on your side, you can send and receive several faxes at once.

Types of eFax Services

Every eFax service uses the same technology — they differ only in where you press Send.

• Email to fax. Write an email, attach the document and address it to the fax number at the provider's domain. Incoming faxes arrive as PDF attachments, and it works from Gmail, Outlook or Apple Mail with no new software. At mFax this is part of mFax Business: every member of the organization faxes from their own sign-in address to <fax number>@send.mfax.to — see how to fax through email.
• Web portal. Log in from a browser, upload the file, type the fax number and send — handy for occasional faxes from a computer.
• Fax app. Photograph a paper document with your phone's camera or pick a PDF from your files, then send it as a fax in seconds. mFax works this way on iPhone, Android, Mac and Windows, and in the browser, with one account and one fax history across all of them.

Teams that need shared numbers, several user accounts and central management look at a cloud fax service, which adds those on top of the same core technology. Our internet fax guide covers the wider provider landscape.

eFax vs. Traditional Fax: Key Differences

The core capability is identical — you send a document that arrives as a fax. Everything else is better with eFax.

The running costs show the gap. A fax machine costs $100–$500 up front, and a dedicated analog line runs around $40 a month before paper, toner and repairs — $50–$100+ a month all in. Online fax services typically cost $8–$25 a month. The best free online fax services guide covers options with free allowances.

How to Send an eFax

1. Choose a service. Pick one that fits how often you fax. The mFax app opens straight to the send screen on your phone or in your browser, and the first 7 days are free.
2. Prepare the document. PDF renders most cleanly on the recipient's end; most services convert Word files, images and scans automatically. To convert a file yourself first, use the free mFax document converter — no signup.
3. Enter the fax number. Type the full number with the country code (+1 for the US) and check it twice. Unlike a mistyped email address, a wrong fax number doesn't bounce back — the fax fails, or reaches the wrong machine.
4. Send and keep the receipt. The service transmits the document and returns a delivery confirmation with the time, the number dialed and the status. Keep it as proof of sending.

The eFax.com Service — What You Should Know

eFax.com is one of the oldest online fax services, founded in 1995. It's well known, widely used in healthcare and legal industries, and owned by a publicly traded company (Consensus Cloud Solutions, NASDAQ: CCSI). That said, "well known" doesn't always mean "best value."

eFax.com Pricing

Overage charges run $0.10 per page beyond your monthly limit. A 7-day free trial is available, but billing starts automatically after it ends.

For detailed pricing analysis, see our eFax Pricing breakdown.

eFax.com Pros and Cons

Pros:

• 30 years in business — established, reliable
• HITRUST certified; HIPAA compliance available (Protect plan)
• Works with email, web browser, or mobile app
• Cloud storage with searchable fax history
• Electronic signature built in
• Fax broadcasting (send to multiple recipients at once)

Cons:

• Expensive for what you get — $18.99/mo for only 170 pages puts it at the high end
• HIPAA compliance requires the most expensive plan ($49.99/mo)
• UI is dated compared to modern alternatives
• Customer complaints about difficult cancellation and surprise billing
• Overage charges can add up quickly for high-volume users

For a full evaluation, read our eFax Review 2026.

Who Uses eFax — and Why?

Faxing may seem outdated, but certain industries never stopped using it:

• Healthcare: 79% of medical facilities still use fax for document exchange. Hospitals, clinics, and insurers exchange patient records, referrals, and prescriptions this way. HIPAA regulations require secure, auditable delivery — and fax (with proper encryption) provides that.
• Legal: 89% of law firms use fax for contracts, court filings, and confidential correspondence. Courts in many jurisdictions still require or prefer fax.
• Financial services: Banks, mortgage companies, and insurance providers rely on fax for compliance documentation.
• Government: Many government agencies only accept faxed submissions for certain forms (including some IRS forms).
• Individuals and small businesses: Tax forms for the IRS, insurance claims, mortgage paperwork — anything where a timestamped delivery receipt matters more than a read receipt.

eFax lets all of these industries keep their fax workflows without maintaining physical fax machines.

Is eFax Safe?

Yes — reputable eFax services are more secure than traditional faxing, not less. Here's why:

• Traditional fax: The document prints and sits on a shared machine tray. Anyone walking by can read it.
• eFax: The document goes directly to a private email inbox or secure portal. Only you see it.

Modern eFax services also encrypt your faxes:

• In transit: TLS 1.2+ encryption (same as online banking)
• At rest: 256-bit AES encryption for stored faxes

Every fax also produces a delivery receipt showing when it was delivered and to which number — proof of sending that an ordinary email doesn't give you.

For HIPAA-regulated environments (healthcare, insurance), look specifically for services that offer a Business Associate Agreement (BAA) — this is a legal requirement, not optional. See our HIPAA eFax comparison for details. mFax Business includes a signed BAA on every plan; for a deeper look at how online fax security works, read Is Online Fax Secure?

A Cheaper eFax Alternative

eFax.com is not your only option — and for most people, it's not the best one either. If you're comparing, here's what to look for:

mFax covers all of these. Send a fax from your phone in under 2 minutes — free for 7 days. Over 5 million users have switched from store faxing and traditional services.

For a practice or office, mFax Business adds a virtual fax number, a signed BAA, email-to-fax and seats for the team across web, mobile and desktop — from about $9/mo billed annually, with a live calculator to build a plan from exactly the seats and pages you need.

For a direct comparison, see mFax vs. eFax or browse the best eFax alternatives if you want a wider list.

Bottom Line

eFax — as a concept — is simply the modern way to fax. It's cheaper to run, more portable, more secure, and requires no hardware. The question isn't whether to use eFax; the question is which eFax service to use.

eFax.com is a solid, well-established choice for large organizations that need brand recognition and HITRUST certification. For individuals and small businesses, cheaper and more modern alternatives offer better value per page.

Ready to send your first eFax? Try mFax.to free for 7 days — upload a document, enter a fax number, and send in under 2 minutes. No fax machine required.