At the end of this posting are some juicy? new clues, in the form of an automatic log from a failed fax.
I hope somebody can use this new information to identify the cause of the problem and find a solution. To my untrained eyes, it looks like it has something to do with unexpected EOF. (Is that end of file?)
SUMMARY OF THE PROBLEM
The following fault has developed with the fax function of OS X (v10.3.9 in my case, and v10.4 in the cases of others in this thread) in the print window:
The fax function successfully makes contact with the receiving number, and then appears to start faxing. However, it then stops faxing, without stating whether it has finished faxing successfully. It then displays a "fax protocol error" message.
The aborted fax then remains in the queue, with "hold until xxxx", i.e. a time 5 minutes later, which is when it will automatically re-try. When it re-tries, the same failure occurs.
The intended recipient does not receive a fax.
NEW CLUES
The new clues came out of my use of the free trial version of the FaxCenter application, v1.5. (FaxCenter is a shareware application, the full version of which costs $10).
The FaxCenter application a "front end" application ("...based on eFax"...) - i.e. it provides a nice interface with the fax function of OS X.
I tried to fax a page of a document using FaxCenter.
The result was: failure - apparently the same failure as described above for the fax function in OS X (i.e. same behavior - I heard the destination fax number being dialled; and then I heard the usual intermittent short beep (about once per second); and then I heard the subsequent high pitched continuous tone from the receiving fax machine; and then the transmission failed, and the message was held for a new try after 5 minutes.)
Following is the log from my last (failed) attempt to fax using FaxCenter. (Note that I have substituted "phone
numberredacted" where the log incuded the number of the receiving fax machine.)
/Applications/FaxCenter/FaxCenter.app/Contents/Resources/fax: eval: line 1: unexpected EOF while looking for matching `''
/Applications/FaxCenter/FaxCenter.app/Contents/Resources/fax: eval: line 2: syntax error: unexpected end of file
/Applications/FaxCenter/FaxCenter.app/Contents/Resources/fax: line 844: make: command not found
/Applications/FaxCenter/FaxCenter.app/Contents/Resources/efax: Mon Jul 17 13:22:05 2006 efax v 0.9.1 Copyright 1999 Ed Casas
efax: 22:13 opened /dev/**.modem
efax: 22:14 using 2.6.3 in class 1
efax: 22:15 dialing T1phone
numberredacted
efax: 23:42 Error: dial command failed
efax: 23:42 failed -> /tmp/send/Output.tif.001
efax: 23:42 done, returning 2 (unrecoverable error)
sed: T1phone
numberredacted.log: No such file or directory
sed: T1phone
numberredacted.log: No such file or directory
G4 iMac Mac OS X (10.3.9)
G4 iMac Mac OS X (10.3.9)