Fax won’t send/receive on MFP — line test & NVRAM reset
Joe B.
Reviewed for technical accuracy
Specialities: Windows 11/10, macOS, Printers & MFPs, Fax/VoIP, Networking, Office Equipment
MFP fax not sending or receiving — analog line, VoIP/T.38, ECM, baud rate, NVRAM reset (HP, Canon, Brother, Epson, Xerox)
Technician
Technician
• Forcing G.711 pass-through or enabling T.38 on the SIP/ATA.
• Lowering the fax baud rate to 14,400 or 9,600 bps and toggling ECM (Error Correction Mode).
• Doing a quick line test: plug an analog phone into the ATA, confirm dial tone, call out and receive a call, then listen for line noise.
If settings look fine, we’ll back up the address book and perform a safe NVRAM/Service reset on the MFP to clear corrupt fax parameters.
Technician
1) In Fax Settings set ECM = On initially. If failures persist, try Off for VoIP jittery links.
2) Set TX/RX speed = 14.4 kbps (V.17). If still failing, step down to 9600 bps.
3) Disable V.34 (Super G3) temporarily — many ATAs struggle with it.
4) Confirm dial prefix (9/0/area code), country/region, and tone/pulse are correct.
5) On the ATA/SIP portal, set T.38 preferred or use G.711 µ-law pass-through; avoid compressed codecs like G.729.
After changes, send a fax test to a known good number (e.g., your provider’s test line) and try receiving.
Technician
• Set Receive Mode = Fax only (or Fax/Tel with Distinctive Ring configured).
• Change Rings to Answer to 2–4. Make sure voicemail isn’t grabbing the call first.
• If using fax forwarding to email or memory receive, clear the fax memory and verify storage isn’t full.
• Check RJ11 wiring — LINE vs EXT ports, no DSL filters on VoIP, proper splitter orientation.
Try an inbound test again.
Technician
• Plug a phone into the wall jack → listen for line noise, crackle, or low volume. If noisy, call the telco.
• Remove splitters/long cords, bypass surge protectors, keep the run short (< 2 m).
• Ensure no DSL filter is on the fax line (unless sharing DSL; then use a splitter correctly).
• Set speed to 14.4/9.6 kbps, ECM on, and disable V.34.
• Update the printer’s firmware. If settings became unstable after power events, we’ll do an NVRAM reset and re-enter the CSID/TSID and country.
Technician
Technician
• Enable T.38 on the trunk/ATA, or lock to G.711 if T.38 is unreliable with your carrier.
• Turn ECM On, V.34 Off, set speed 14.4 kbps (drop to 9.6 if needed).
• Disable fax “JBIG” compression if the driver supports it. Keep echo canceller off on the ATA.
• Use short, good-quality RJ11 cables; connect to the LINE port (not EXT).
• Coordinate with ISP to avoid bandwidth shaping; prioritize the ATA/QoS.
Save those as a preset so a power cycle doesn’t revert them.
Technician
Technician
• Canon: Menu → Fax Settings → TX/RX Settings. Maintenance → Initialize All Data/Settings for NVRAM; backup via Remote UI.
• Brother: All Settings → Fax → Setup Receive/Transmission. Init/Reset → Factory Reset; use Web Based Management for export.
• Xerox: App Settings → Fax; Device → Resets → NVRAM. Firmware via CentreWare IS.
If you’d like, I can remote you to the exact screens.
Technician
Quick answer: the accepted fix
Accepted fix when fax won’t send/receive on MFP (analog or VoIP): run a line test, enable ECM, set TX/RX speed to 14.4 → 9.6 kbps, turn V.34 Off, configure T.38 or G.711 pass-through on the ATA, verify receive mode and rings, then update firmware. If settings are unstable, backup and perform NVRAM reset, then re-enter CSID/TSID and fax header.
Fax failed after provider change or firmware update (error 232/344/346)
Carrier or firmware changes often switch codecs and break fax over VoIP. Re-provision the ATA/SIP trunk for T.38 or G.711, lower the baud rate and toggle ECM. If the MFP lost region or dial settings, perform a service/NVRAM reset and reconfigure country code, dial prefix, receive mode.
How to verify fax send/receive
Send a 1-page fax test to a known good number, then call your fax line to confirm auto-answer. If it still fails, plug in a handset and check for line noise, try 9.6 kbps, and make sure voicemail isn’t picking up first. With VoIP, confirm the trunk shows T.38 active during the session.
MFP fax troubleshooting tips
Most fax issues are codec/speed mismatch on VoIP or incorrect receive settings.
Quick path: line test → ECM On → speed 14.4/9.6 → V.34 Off → T.38 or G.711 → verify rings/receive mode → firmware update → NVRAM reset if configs are corrupted. Brand menus: HP, Canon, Brother, Xerox. Common terms: RJ11 wiring, SIP trunk, ATA, error 232/344/346, CSID/TSID.
Disclaimer: This information is AI-generated and intended for general guidance only. For advice specific to your environment, please consult a verified expert on Whizz-Tech before making decisions.
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FAQ
Why won’t my MFP fax send or receive on VoIP?
Usually the SIP/ATA isn’t using T.38 or G.711 pass-through, or the device is set to V.34 (Super G3) at full speed. Enable T.38/G.711, set ECM On, lower baud rate (14.4/9.6), and verify receive mode and rings.
What is a line test and how do I do it?
Plug an analog handset into the LINE port (or ATA). Confirm dial tone, call out and receive a call, and listen for noise/crackle. If noisy on POTS, contact the telco. With VoIP, check the provider portal that T.38 negotiated.
When should I use an NVRAM reset?
Use it when fax settings become corrupted or won’t stick after firmware changes. Back up the address book/CSID first, perform the reset, then reconfigure ECM, speed, V.34, country, dial prefix.
Can voicemail stop faxes from receiving?
Yes. If voicemail answers before the MFP, set Rings to Answer lower (2–4), change to Fax only mode, or configure Distinctive Ring.
Brand tips for HP / Canon / Brother / Xerox?
Menus vary, but look for Fax Settings → ECM/V.34/Speed, Receive Mode, and Rings to Answer. Use the device’s web UI to back up before an NVRAM reset and apply the latest firmware.
| Symptom | Likely cause | Quick fix |
|---|---|---|
| Fax won’t send (error 344/232) | VoIP codec mismatch or noisy POTS line | Enable T.38/G.711, set ECM On, lower speed to 14.4/9.6, V.34 Off; test line |
| Can’t receive faxes | Wrong receive mode/rings; voicemail intercepts | Set Fax only, 2–4 rings, disable voicemail or use Distinctive Ring |
| Fax picks up but fails mid-page | Jitter/packet loss on VoIP or bad RJ11 cable | QoS for ATA, shorten cable, try G.711 pass-through or T.38 |
| Settings won’t stick | Corrupted configuration | Backup, update firmware, then perform NVRAM reset and reconfigure |
Step-by-step (quick path)
- Run a line test with a handset; fix wiring, filters, or voicemail conflicts.
- On the MFP: ECM On, V.34 Off, speed 14.4 → 9.6 kbps, verify dial prefix and country.
- On VoIP: enable T.38 or lock to G.711; disable echo cancel/noise suppression for the fax port.
- Update firmware. If unstable, backup and NVRAM reset, then restore settings/address book.
Sources
- HP — Fax setup & troubleshooting
- Brother — Fax send/receive issues
- Canon — Fax (TX/RX) settings & errors
- Xerox — Fax over VoIP guidance
Filed under: Scanning / Fax / Scan-to-email / Scan-to-cloud
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