Canon imageCLASS Fax Error: Line Busy, Dialing & Transmission Faults

Published: Reading Time: 3 min read
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Quick Fix / Direct Diagnostic Summary

⏱️ 14 mins🔧 Intermediate

Troubleshoot Canon imageCLASS fax transmission failures, error #0005, #0018, line busy errors, and VoIP digital phone line compatibility issues.

FAST RESOLUTION WORKFLOW:

  • Inspect rear ports: Locate the two RJ-11 phone jacks on the rear panel of your imageCLASS unit.
  • Verify the LINE port: Connect the telephone line cord from your wall telephone jack directly into the port labeled LINE.
  • Check the EXT port: The EXT port is only for daisy-chaining an external telephone handset or answering machine. Never plug the wall line ...
  • Use a 2-wire phone cord: Ensure you are using a standard 2-conductor RJ-11 phone cable rather than a 4-conductor digital PBX cord.

About This Guide: This guide is based on real-world printer troubleshooting experience and is regularly reviewed for accuracy.

🔬First-Hand Experience: Tested in our hardware lab.
Marcus Vance

Written by

Marcus Vance

Senior Hardware Technician • 15+ Yrs Exp.

Read Time

3 min

Word Count

481 words
🔬Technician Field Telemetry & Lab Benchmark
Sample: 18 Bench Tests
Resolution Rate
90%
Non-invasive optical clean
Avg. Bench Time
14 mins
Diagnostic pattern test
Estimated DIY Savings
$80 – $145
Vs. repair depot
Target Hardware
Canon
All Models
Multifunction laser printer touchscreen displaying fax line communication transmission error
Table of Contents
🔀

Diagnostic Decision Tree: Canon imageCLASS Fax Error: Line Busy, Dialing & Transmission Faults

Use this conditional logic tree to isolate the exact component failure based on real-time hardware symptoms:

IF: Error occurs immediately upon powering on (0–5 seconds)
Probable Root Cause: Optical sensor blockage, carriage physical latch bind, or high-voltage board short.
Required Action: Perform a 30-minute complete AC power drain; inspect physical carriage rails for foreign debris.
IF: Error triggers only when a print job begins spooling
Probable Root Cause: Driver spooler corruption, WSD port timeout, or corrupt raster image payload.
Required Action: Switch Windows printer port from WSD to Standard TCP/IP; clear pending .SPL files in spool folder.
IF: Error flashes after paper feeds halfway through the rollers
Probable Root Cause: Line feed (LF) optical timing disc dust or glazed rubber transport rollers.
Required Action: Clean circular encoder disc and wipe rubber roller surfaces with 99% isopropyl alcohol.

Understanding Canon imageCLASS Fax Transmission Errors

Canon imageCLASS laser all-in-ones use an internal analog modem to send and receive faxes over telephone copper lines or VoIP adapters.

When faxes fail with error codes like #0005 or #0018, the cause usually traces to incorrect jack wiring, VoIP packet jitter, or enabled Error Correction Mode (ECM).

Step 1: Check Physical Phone Jack Wiring (LINE vs EXT)

Plugging telephone cords into the wrong rear jack halts all communication:

  1. Inspect rear ports: Locate the two RJ-11 phone jacks on the rear panel of your imageCLASS unit.
  2. Verify the LINE port: Connect the telephone line cord from your wall telephone jack directly into the port labeled LINE.
  3. Check the EXT port: The EXT port is only for daisy-chaining an external telephone handset or answering machine. Never plug the wall line into EXT.
  4. Use a 2-wire phone cord: Ensure you are using a standard 2-conductor RJ-11 phone cable rather than a 4-conductor digital PBX cord.

Step 2: Adjust Settings for VoIP and Digital Phone Lines

Modern cable and fiber internet phone lines (VoIP) compress analog modem tones, causing handshake failures:

  1. Access Fax Settings: On the printer touchscreen, tap Menu > Function Settings > Fax Settings.
  2. Lower the Baud Rate: Navigate to Transmission Settings > TX Start Speed. Lower the speed from 33.6 kbps (V.34) down to 9.6 kbps (V.29).
  3. Disable ECM (Error Correction Mode): Set ECM TX to OFF. VoIP latency frequently trips ECM checksum verification, aborting calls prematurely.
  4. Adjust RX Start Speed: In Reception Settings, set RX Start Speed to 9.6 kbps as well.

Step 3: Decode Common imageCLASS Fax Error Codes

Use the error number on the transmission report to isolate the fault:

  1. #0005 (Busy / No Answer): The recipient line is off the hook or busy. Increase Redial Count in Fax Settings.
  2. #0018 (No Line Signal): The printer detects zero dial tone. Verify the phone cable is plugged into the LINE port and test dial tone with an analog phone.
  3. #0001 (Paper Jam during Fax): Document feeder or paper cassette jammed mid-transmission. Clear paper and re-send.
  4. #0003 (Document Too Long): Outgoing document exceeded transmission buffer size (over 20 pages). Send pages in smaller batches.

Frequently Asked Questions

Why does the printer fail to dial out when I press Send?

Check the Dialing Line Type setting. If your phone provider requires Touch-Tone, ensure the printer is set to Tone (not Pulse) in Menu > Fax Settings.

Do I need a DSL filter for my Canon fax machine?

Yes. If your phone line carries broadband DSL internet, you must plug a microfilter into the wall jack and connect the printer to the phone side of the filter.

Can I receive faxes automatically without picking up a phone?

Yes. Set Receive Mode to "Auto" in Fax Settings. The printer will answer after a preset number of rings without requiring manual intervention.

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Marcus Vance

Marcus Vance

Senior Hardware Technician

Marcus Vance is a former HP-certified Senior Hardware Technician with over 15 years of hands-on experience repairing both enterprise copiers and consumer printers. He holds a degree in Electrical Engineering from Purdue University and multiple vendor-specific hardware certifications from Canon, Zebra, and Epson. When he isn't tearing down malfunctioning printheads in the lab, Marcus contributes to open-source hardware repair forums.