Short answer: the traditional copper telephone network that carried faxes is being retired across Europe and North America, and customers are moved to internet telephony. Fax tones survive that move badly unless the equipment uses a dedicated protocol, T.38, or a very clean voice path. For a small office, the choices are to configure the machine properly, to replace it with software, or to send from a browser.
If your fax machine suddenly "stopped working" and the machine itself is fine, the cause is very often the line. Many providers have quietly replaced the copper pair with a fiber or cable connection, and the voice service now travels as data.
Why fax and VoIP do not get along
A fax call is not a conversation; it is a modem transmission. The two machines exchange tones and send data at a fixed pace. A voice-over-IP network is designed for the human ear. To save bandwidth it compresses audio, drops tiny gaps in the signal and tolerates small variations in timing, all of which a person never notices.
For a fax, each of these is damaging:
- Compression distorts the modem tones.
- Packet loss and jitter corrupt lines of the page or break the session.
- Echo cancellers, built for speech, can interfere with the handshake.
The symptoms are familiar: pages with black bands, transmissions that stop at page two, or a machine that reports "communication error" about one fax in three.
What T.38 does
T.38 is an international standard that solves the problem at the root. Instead of sending the fax tones as audio, an adapter or gateway demodulates them into data at your end, sends that data across the internet in a protocol designed for reliability, and a gateway at the far end re-creates the tones for the receiving machine.
Three things must line up for T.38 to work: your adapter must support it, your telephone provider must carry it, and the recipient's side must handle it. If any link falls back to ordinary audio, quality drops. This is why a fax that works to one correspondent fails to another.
Options for a small office
1. Keep the machine and add an adapter
A VoIP telephone adapter (often called an ATA) connects an analog fax machine to your router. Look for T.38 support, and for a setting that forces the fax mode, for example disabling echo cancellation and fixing the codec to G.711. A modest VoIP adapter with T.38 support is the usual hardware. Test with several real pages and with several destinations, not just one.
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2. Move the fax to a server or an online service
A software fax server or a cloud service does away with the machine. Documents leave from a PC or an app, and incoming faxes arrive as PDFs. This avoids paper, toner and the line problem, at the price of a subscription for reception. See how receiving works.
3. Send from the browser when you only need to send
If your problem is outbound, a browser removes the whole stack. You upload the file, type the number and the service dials from a platform that is built for it. There is nothing to configure and nothing to repair. The pricing is per document, with a single page free, which suits occasional use better than a contract. Check which countries are served.
A practical test before you decide
- List the destinations you really fax in a typical quarter.
- Send three or four test pages from the current setup to each, including one with small print.
- Note failures and their timing. A pattern (always long documents, always one country) points to settings. Random failures point to the line.
- If more than one fax in ten fails, stop adjusting and change approach.
What to ask your telephone provider
- Is my line still on copper, and is there a switch-off date?
- Does my plan include a fax-compatible mode or T.38?
- Can I keep my number if I change provider?
- Is there an analog port on the box, and what is the voice codec?
Providers answer more precisely when asked for a "fax-compatible" line rather than for "a phone line".
Frequently asked questions
Will my old machine stop working?
Not necessarily. If it is connected to a line that is still analog, or to an adapter configured for fax, it works. The risk is that you do not control the date a provider migrates your line.
Is T.38 secure?
It carries the same pages as an ordinary fax; it is not an encryption standard. Use a provider that protects the signaling and the network, and treat sensitive documents with care. See our security page.
Do I need to tell recipients I changed technology?
Not usually, but ask important contacts to confirm the first fax arrived.
Key points
- Copper is being retired, and voice over IP is not designed for fax tones.
- T.38 transports fax as data and is the reliable route if the whole chain supports it.
- Test with real pages before relying on any setup.
- For sending only, a browser is the least maintenance.
Topicsfaxvoip
