External USB Modem fax not working under 10.5.8

Question

I upgraded my Mac Mini home office server (print, fax, backup) to 10.5.8 and now it appears that faxing is completely broken (or maybe the USB modem driver.)
I've verified that this is broken on another system.
After booting, the following is seen in the fax log:
efax: 33:57 command "+FAR=1"
efax: 33:57 waiting 5.0 s
efax: 33:57 .956 [<CR><LF>ERROR<CR><LF>]
efax: 33:57 response "ERROR"
efax: 33:58 command "S0=1"
efax: 33:58 waiting 5.0 s
efax: 33:58 .157 [<CR><LF>OK<CR><LF>]
efax: 33:58 response "OK"
efax: 33:58 waiting for activity
efax: 33:59 activity detected
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 command "Q0V1"
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 waiting 2.0 s
efax: 34:00 waiting 2.0 s
efax: 34:00 command "Q0V1"
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 waiting 2.0 s
efax: 34:00 sync: dropping DTR
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 waiting 2.0 s
efax: 34:00 command "Q0V1"
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 waiting 2.0 s
efax: 34:00 sync: sending escapes
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 Error: tcsetattr on fd=5 failed: Invalid argument
efax: 34:00 Error: fax device write: Input/output error
efax: 34:00 Error: fax device write: Input/output error
efax: 34:02 Error: fax device write: Input/output error
efax: 34:02 waiting 2.0 s
efax: 34:02 command "Q0V1"
efax: 34:02 Error: fax device write: Input/output error
efax: 34:02 waiting 2.0 s
efax: 34:02 Error: sync: modem not responding
efax: 34:03 done, returning 2 (unrecoverable error)
Anybody else seeing this?

Answer 1

This solution is a "workaround" and will not affect in any problems, like I saw that they will happen after:
1.) Removing and changing "IOSerialFamily.kext" : ("The system extension '/System/Library/Extensions/IOSerialFamily.kext' was installed improperly and cannot be used....")
2.) or go back to OS 10.5.5... (latest security-updates not included)
Go to your System-Prefs -> Printing and Faxing
chose the Fax-Modem -> Options
1.) to receive faxes: choose "receive faxes on this computer"
2.) to send faxes: choose not to "receive faxes on this computer",
plug your modem out, wait 5 seconds and plug it in.
Now you can send faxes, but not receive,
before you choose "receive faxes on this computer" again.
To send, you have to start with 2.) again...
It's strange for a mac, but better than 10.5.5 or a corrupted system...
APPLE-STUFF: HERE AGAIN: FIX THAT FAX-PROBLEM FOR 10.5.8 QUICK PLEASE - IT'S IMPORTANT!!!
trollius