Anytime you send a fax you will receive a receipt to indicate if the fax was successful or not.
If a failure occurs the receipt will contain the reason for the failure as well as the message header of the sent fax.
The following is one of the possible failure notices that could occur.
Transmission Failed
The 'fax transmission failed' receipt indicates that the outbound fax failed after myCloudPBX attempted to send it 5 times.
Common causes of fax failure:
- The fax number is incorrect.
- The fax number is unreachable and does not answer the call from the PBX.
- The receiving fax machine is attempting to use a high speed transmission mode that is not compatible with the PBX.
- The receiving fax machine is using Error Correction Mode (ECM).
TIPS:
- Confirm with the intended recipient that the number is correct.
- Give the number a ring from a mobile and confirm that the number is actually a fax machine. (In this example the number is not a real fax number, which is why it failed).
- If possible, have the receiving fax machine set their transmission speed for both send & receive to 9600bps.
- If possible, have the receiving fax machine disable Error Correction Mode (ECM).
- Try again in 5 minutes.
The Virtual Fax feature is provided on an “as-is” basis without warranty or expectation of usability. As the Virtual Fax feature operates over a Voice Over IP network there may be certain circumstances where a fax fails. When this occurs there is no ability for us to correct, recover or improve the facility.
More about Error Correction Mode (ECM):
When there is noise or poor call quality on the fax call, parts of the transmission may become corrupted or lost in transit.
ECM looks at the data received and will request a re-transmission of the corrupted data until it receives an error free copy of the data.
When a line is particularly bad, these retransmissions can drastically increase the length of the call, and in the worst case can lead to a failure with a Communication Error being reported by receiving fax machine.
By disabling ECM, we can increase the chances of the receiving fax machine accepting the transmission even if some of the data is not perfect due to the interference.