Mobile fax function returns SFAPI_LE_05 error sending to a working fax number with a fax tone.

[Todddy23]

SmartTank 7600 doesn't send Mobile fax to a working fax machine with carrier tone.  Multiple attempts.

[Hawks_Eye]

Hi @Todddy23 

Welcome to the HP Support Community! We're here to help you get back up and running.

I'm really sorry your SmartTank 7600 is returning the SFAPI_LE_05 error when trying to send a mobile fax—it’s frustrating when everything seems ready, the tone is present, but the transmission still fails. This error typically points to a handshake failure between the mobile fax service and the receiving machine. 

Let’s walk through a few steps to help restore smooth fax delivery.

What SFAPI_LE_05 means:

This error indicates that the receiving fax machine answered, but the connection couldn’t be completed. It may be due to:

• A non-standard fax tone or delay in tone detection
• Carrier-level interference or codec mismatch
• Timing issues between the mobile fax service and the recipient’s machine

Even if the tone is audible, the handshake may not meet the expected protocol.

Try these steps to improve fax delivery:

1. Verify the fax number format

Use the full international format if applicable:

• For India: +91 followed by the number
• Avoid spaces, dashes, or brackets
• Example: +911234567890

 

2. Send a test fax to HP’s internal test line

This confirms whether your mobile fax setup is functioning:

• Open the HP App
• Go to Mobile Fax > Send Fax
• Use HP’s test number: +1 888 473 2963
• Attach a simple document and send

If this succeeds, the issue is likely with the recipient’s line or timing.

 

3. Try sending at a different time

Some fax machines respond differently depending on line load or auto-answer settings.

• Wait 10–15 minutes and retry
• Avoid peak hours when line congestion may affect transmission

 

4. Use a different document format

Sometimes large or complex PDFs can cause delays in transmission.

• Try sending a simple one-page PDF or image file
• Avoid scanned documents with high resolution or embedded fonts

 

5. Check your internet connection

Mobile fax relies on a stable connection to HP’s cloud service.

• Ensure your device is on Wi-Fi, not mobile data
• Avoid VPNs or firewalls that may block outbound fax traffic

 

6. Review HP’s Mobile Fax Error Code Guide

This document outlines all error codes and their meanings:

• HP Mobile Fax Error Codes PDF

Let me know how your SmartTank 7600 responds after trying the test fax and adjusting the format. Once the handshake completes successfully, you’ll be able to send documents with confidence and clarity.

If my response helped, please mark it as an Accepted Solution! ✅ It helps others and spreads support. 💙 Also, tapping "Yes" on "Was this reply helpful?" makes a big difference! Thanks! 😊

Take care, and have an amazing day!

Regards, 

Hawks_Eye