I have a 3050 (20k copies) with fax system M. Outgoing faxes fail at about a 50% rate. Listening to the device, I know that it is not dailing. When the faxes are successful I hear the dailing and handshake. I have replaced the fax board, same result. I have added dashes between the numbers, turned off busy detect. A desktop fax at the clients works fine. Any settings I can adjust? I am not ruling out the clients phone lines, but I must eliminate our machine first.

lower the baud rate

Have the phone company check the line for noise.

Is the phone line shared with anything else?
I had a customer that was having a problem intermittently with faxes not going through to known good #s. yet, a standalone Panasonic fax had no issues. I swapped the card out, the phone company checked the line to no avail. We found out later that the line was being shared with the alarm system in the building. This was causing interference in the way of a very low tone beep. This in turn was affecting the fax. We couldnt hear it but the fax would handle the sound as an answer on the receiving fax.

If you swapped the card and they are still having issues, the card and machine are most likely not the problem. The customer needs to troubleshoot from that point.

A good tip for Falcon 3 machines where the Fax line comes through an internal Digital Phone System is to attach a DSL Filter to the Modem wire! - Sounds unnecessary but these Fax Systems are very susceptable to 'interference' and 'noise'. This tip from Kyocera UK after dealer feedback...
May be worth a try!
Regards,
Mark

Thanks to all. We had a phone expert look at it and thinks theres too much compression on the lines and its the responsibility of the phone provider to clean it up. This place however is an ancient building, a birds nest of wires and cabling, so maybe something is screwed up internally.

Its got to the point where we stopped going the extra mile and said "our machine works, fix your own mess here."

Ive seen fax Ms go goofy when installed in OPT2 rather than OPT1. Just heads up.