1. Call the number to confirm a proper fax tone
2. If fax forwarding is enabled, call both numbers and note the results
3. From the fax status page review failure vs success rates
   • A 5% failure rate is common, 7.5% is acceptable, 10% or more is a bit high. This information is helpful to know when analyzing fax transmission failure rates. Please see a real example below regarding one of our numbers.
     • There were 390 total inbound jobs to the number over 10 days. Out of 390 jobs, 21 jobs resulted in a receive-failed status. All 21 failed jobs show the error message - "hangup," which is a very common error in telephony, simply meaning the call was ended from either end before the fax was completely able to transmit.
     • 21 out of 390 is a failure rate of 5.38% which is in the common to acceptable window.
     • I called the number and received a healthy fax tone.
     • Based on this information, the line is healthy. If the sending environments are consistently getting hangup errors when sending to this number, I would suggest having them try a different line to see if the issues are consistent.
   • High failure (10% or more) from various external numbers is a possible indication of a problem with an internal number. In this case, it is best to provide Softlinx support with a few fax ID examples within the past 24 hours, if possible. Then Softlinx support can reach out to our carrier to further investigate.
   • High failure (10% or more) from 1 or 2 external numbers is a possible indication of bad external numbers – in this case, the external carriers/users would need to troubleshoot.