How to Dial a Fax Number (Local, Long Distance & International)

By Sarah Martinez · Published October 8, 2025 · Updated March 15, 2026 · 8 min read

Quick Answer: How to dial a fax number depends on where you're sending from and to. For local US faxes, dial the 10-digit number. For long distance, add "1" at the front. For international, use "011" + country code. For office PBX systems, dial "9" first. Using mFax — an online fax app — eliminates all prefix rules entirely.

You have the document. You have the fax number. But the machine keeps failing to connect.

Nine times out of ten, the problem isn't the machine — it's how the number was dialed. A missing "1", a forgotten exit code, or an office system that requires "9" before any outbound call will silently kill your transmission.

This guide covers every dialing scenario, so your fax goes through on the first try.

Understanding a Fax Number: What Each Part Means

Before dialing, it helps to know what you're looking at. A US fax number has three distinct parts:

Together: +1 (212) 555-0199

In the US and Canada, fax numbers are 10 digits long (area code + 7-digit number). International numbers are longer because they include the country code. For a deeper look, see our guide on fax number formats and how to write them correctly.

Scenario 1: You're Using an Online Fax App

Difficulty: Easy — just type the number

If you're using mFax or another online fax service, the dialing rules are dramatically simpler:

• Local or long-distance (US/Canada): Enter the 10-digit number — (212) 555-0199
• International: Use the + format — +44 20 7946 0958

That's it. The service handles all exit codes, long-distance prefixes, and routing internally. You never need to think about "9", "1", or "011".

This is the biggest practical advantage of online faxing: you don't need to know dialing rules. Just enter the number as it appears on the business card or letterhead.

Try mFax — enter the number, upload your document, and send. No dialing rules needed.

Scenario 2: Dialing a Local Fax (Physical Machine)

Difficulty: Easy

For a fax within your local area code using a home or small-office machine:

• Dial the 10-digit number (area code + 7-digit number)
• Example: (415) 555-0174 → dial 4155550174

Important: Since the FCC mandated 10-digit dialing across the US in 2021, you can no longer skip the area code — even for a neighbor down the street. If you try 7-digit dialing, most exchanges will reject the call.

Scenario 3: Dialing Long Distance in the US or Canada

Difficulty: Easy — add "1" at the front

When faxing to a different area code (or sometimes even the same area code in a different rate zone), physical fax machines require the long-distance prefix:

• Format: 1 + area code + 7-digit number
• Example: 1-415-555-0174

The "1" is the country code for the North American Numbering Plan (NANP), which covers the US, Canada, and several Caribbean nations. Physical machines use it to route the call through long-distance carriers.

Scenario 4: Dialing from an Office with a PBX System

Difficulty: Medium — dial "9" (or "8") first

If you're in a corporate office, hotel, or large institution, your phones likely run through a PBX (Private Branch Exchange) — an internal phone system that manages dozens or hundreds of extensions.

To make an outside call from a PBX, you typically need an access code first:

• Dial "9" then wait for a second dial tone, then dial the full number
• Some older systems use "8" instead of "9"
• Full sequence: 9 → 1 → area code → number
• Example: 9 1 212 555 0199

How to confirm your office prefix

Not sure if your office uses "9" or something else?

1. Pick up the handset and listen for a dial tone
2. Dial "9" — if you hear a second dial tone, "9" is your outside line prefix
3. If nothing happens or you hear a busy signal, try "8" or ask your IT department
4. Some modern VoIP office systems have eliminated the prefix entirely — just dial the number directly

A note on pauses

On older PBX systems, you may need to pause between the access code and the main number to give the system time to switch to an outside line. On a physical machine, this is often programmed as a comma (,) in the speed dial entry, which inserts a 2-second pause.

Scenario 5: Dialing an International Fax

Difficulty: Medium — exit code + country code + number

International faxing requires an exit code (to get out of the domestic phone network) followed by the destination country code.

From the United States or Canada

From Europe or Most of the World

Most countries outside North America use 00 as the exit code instead of 011:

• Format: 00 + country code + number
• Example (UK to US): 00 1 212 555 0199

The Universal Shortcut: Use "+"

The + symbol works universally regardless of which country you're dialing from. It automatically represents whatever exit code applies to your location.

• Format: + + country code + area code + number
• Example: +44 20 7946 0958 (US to UK)
• Example: +1 212 555 0199 (anywhere to US)

This format works on all online fax services and modern mobile-connected fax devices. It's the most reliable format because it eliminates exit code confusion.

Common Country Codes

For a complete international dialing guide with rates and tips, see our complete guide to international faxing.

Quick Reference Cheat Sheet

Common Dialing Mistakes (and How to Fix Them)

Even experienced fax senders run into these:

Troubleshooting: When the Fax Still Won't Connect

If you've dialed correctly and the fax still fails, here are the next things to check:

• Busy signal: The recipient's machine is occupied. Try again in 5–10 minutes. Online fax services like mFax automatically retry.
• "No Answer" or "No Carrier": The number may be a voice line, not a fax line. Confirm the number with the recipient.
• "Communication Error": Common on VoIP phone lines. Traditional fax machines often have reliability issues over internet-based phone lines. Switching to a wireless fax method eliminates this entirely.
• Fax cuts out mid-transmission: The call may be dropping due to a poor connection or line noise. Try during off-peak hours or use an online service.

The Case for Skipping Dial Rules Entirely

Physical fax machines require you to know:

• Whether you're on a PBX and what your access code is
• Whether the destination is local, long distance, or international
• Which exit code your country uses
• Whether the receiving country's area code has a leading zero to drop

Online fax services know all of this automatically. You enter the number; the service figures out the routing.

For anyone who faxes occasionally — or even regularly — tools like mFax remove the entire dialing layer. Upload your document, enter the number in standard format, and send. The transmission success rate is higher too, since the service automatically retries failed attempts.

If you need faxing without a traditional phone line at all, see our guide to faxing without a phone line.

Send Your Fax Now

Now that you know how to dial a fax number in every situation, the fastest path forward is:

1. For a physical machine: Use the cheat sheet above for your specific scenario
2. For online faxing: Visit mFax.to, upload your document, enter the number with area code (add + and country code for international), and send

No machine. No memorized prefix codes. No retry loops.

Try mFax — over 5 million users fax from their phone or browser in under 2 minutes.