Failure to send fax with USRobotics 56K message modem

(On a dual boot machine where windows XP successfully sends fax dectecting the 3Com - U.S.Robotics 56K Message Modem as a Sportster PnP).

Tried both using efax and fax from the command line and withe kdeprintfax
both as user and as root

the modem starts to dial and then hangs very soon. See logs below.
I also tried to fiddle with /etc/efax.rc which fax uses to invoke efax
Googling did not help.
I guess the modem requires some init string which the Windows software guesses but the Linux one doesn't.

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KDEPrint Fax Tool Log

Converting input files to PostScript

Mime type: text/plain
Command: enscript -M %psu -E -p %out %in
[ 1 pages * 1 copy
left in /tmp/kde-edoardo/kdeprintfax_RUhFloLR

Sending fax to 01962815576 ()

Sending to fax using: /usr/bin/fax NAME="'EComarEVorisi'" DEV='modem' PAGE='a4' FROM='00442083906262' send '01962815576' '/tmp/kde-edoardo/kdeprintfax_RUhFloLR'
/tmp/kde-edoardo/kdeprintfax_RUhFloLR is postscript...
efax: Fri Jan 13 11:40:20 2006 efax v 0.9a-001114 Copyright 1999 Ed Casas
efax: 40:20 opened /dev/modem
efax: 40:23 using U.S. Robotics 56K Message Rev. 12.1.12 U.S. Robotics 56K Message OK OK in class 2.0
efax: 40:25 dialing T01962815576
efax: 42:33 Error: dial command failed
efax: 42:33 failed -> /tmp/kde-edoardo/kdeprintfax_RUhFloLR.001
efax: 42:33 done, returning 2 (unrecoverable error)
There were errors (see T01962815576.efax.log).

====================================================================
efax: Fri Jan 13 11:40:20 2006 efax v 0.9a-001114 Copyright 1999 Ed Casas
efax: 40:20 compiled Oct 28 2005 13:46:13
efax: 40:20 TIFF version 4.2 file (little-endian)
efax: 40:20 TIFF directory at 8 with 20 tags, last image.
efax: 40:20 page 1 : /tmp/kde-edoardo/kdeprintfax_RUhFloLR.001 + 338 : 1728x2292 @ 204x196 dpi TIFF/FAX
efax: 40:20 argv[0]=efax
efax: 40:20 argv[1]=-v
efax: 40:20 argv[2]=ewin
efax: 40:20 argv[3]=-v
efax: 40:20 argv[4]=chewmainrxtf
efax: 40:20 argv[5]=-d/dev/modem
efax: 40:20 argv[6]=-x
efax: 40:20 argv[7]=/var/lock/LCK..modem
efax: 40:20 argv[8]=-iZ
efax: 40:20 argv[9]=-i&FE&D2S7=120
efax: 40:20 argv[10]=-i&C0
efax: 40:20 argv[11]=-iM1L0
efax: 40:20 argv[12]=-l
efax: 40:20 argv[13]=00442083906262
efax: 40:20 argv[14]=-kZ
efax: 40:20 argv[15]=-h
efax: 40:20 argv[16]=2006/01/13 11:40 00442083906262 EComarEVorisi p. %d/%d
efax: 40:20 argv[17]=-t
efax: 40:20 argv[18]=T01962815576
efax: 40:20 argv[19]=/tmp/kde-edoardo/kdeprintfax_RUhFloLR.001
efax: 40:20 created text lock file /var/lock/LCK..modem
efax: 40:20 opened /dev/modem
efax: 40:20 command "Q0V1"
efax: 40:20 waiting 2.0 s
efax: 40:20 .422 [OK]
efax: 40:20 response "OK"
efax: 40:20 command "Z"
efax: 40:20 waiting 5.0 s
efax: 40:20 .655 [OK]
efax: 40:20 response "OK"
efax: 40:20 command "&FE&D2S7=120"
efax: 40:20 waiting 5.0 s
efax: 40:20 .894 [OK]
efax: 40:20 response "OK"
efax: 40:20 command "&C0"
efax: 40:20 waiting 5.0 s
efax: 40:21 .127 [OK]
efax: 40:21 response "OK"
efax: 40:21 command "M1L0"
efax: 40:21 waiting 5.0 s
efax: 40:21 .362 [OK]
efax: 40:21 response "OK"
efax: 40:21 command "E0"
efax: 40:21 waiting 5.0 s
efax: 40:21 .595 [OK]
efax: 40:21 response "OK"
efax: 40:21 command "I3"
efax: 40:21 waiting 5.0 s
efax: 40:21 .704 [U.S. Robotics 56K Message Rev. 12.1.12]
efax: 40:21 .851 [OK]
efax: 40:21 response "OK"
efax: 40:21 command "+FCLASS=?"
efax: 40:21 waiting 5.0 s
efax: 40:22 .086 [0,1,2.0]
efax: 40:22 .217 [OK]
efax: 40:22 response "OK"
efax: 40:22 command "+FCLASS=2.0"
efax: 40:22 waiting 5.0 s
efax: 40:22 .455 [OK]
efax: 40:22 response "OK"
efax: 40:22 command "+FMI?"
efax: 40:22 waiting 5.0 s
efax: 40:22 .689 [U.S. Robotics 56K Message]
efax: 40:22 .829 [OK]
efax: 40:22 response "OK"
efax: 40:22 command "+FMM?"
efax: 40:22 waiting 5.0 s
efax: 40:23 .063 [OK]
efax: 40:23 response "OK"
efax: 40:23 command "+FMR?"
efax: 40:23 waiting 5.0 s
efax: 40:23 .424 [OK]
efax: 40:23 response "OK"
efax: 40:23 using U.S. Robotics 56K Message Rev. 12.1.12 U.S. Robotics 56K Message OK OK in class 2.0
efax: 40:23 command "+FIP"
efax: 40:23 waiting 5.0 s
efax: 40:23 .784 [OK]
efax: 40:23 response "OK"
efax: 40:23 command "+FNR=1,1,1,0"
efax: 40:23 waiting 5.0 s
efax: 40:24 .023 [OK]
efax: 40:24 response "OK"
efax: 40:24 command "+FLO=1"
efax: 40:24 waiting 5.0 s
efax: 40:24 .260 [OK]
efax: 40:24 response "OK"
efax: 40:24 command "+FBO=0"
efax: 40:24 waiting 5.0 s
efax: 40:24 .497 [OK]
efax: 40:24 response "OK"
efax: 40:24 command "+FCR=1"
efax: 40:24 waiting 5.0 s
efax: 40:24 .733 [OK]
efax: 40:24 response "OK"
efax: 40:24 command "+FIS?"
efax: 40:24 waiting 5.0 s
efax: 40:24 .867 [1,5,0,2,0,0,0,5]
efax: 40:25 .001 [OK]
efax: 40:25 response "OK"
efax: 40:25 command "+FLI=" 00442083906262""
efax: 40:25 waiting 5.0 s
efax: 40:25 .149 [OK]
efax: 40:25 response "OK"
efax: 40:25 dialing T01962815576
efax: 40:25 command "DT01962815576"
efax: 40:25 waiting 120.0 s
efax: 40:33 .163 [NO DIAL TONE]
efax: 42:33 Error: dial command failed
efax: 42:33 failed -> /tmp/kde-edoardo/kdeprintfax_RUhFloLR.001
efax: 42:33 command "Q0V1"
efax: 42:33 waiting 2.0 s
efax: 42:33 .544 [OK]
efax: 42:33 response "OK"
efax: 42:33 command "Z"
efax: 42:33 waiting 5.0 s
efax: 42:33 .787 [OK]
efax: 42:33 response "OK"
efax: 42:33 read HDB pid 4131 [ 4131] from /var/lock/LCK..modem (our pid)
efax: 42:33 removed lock file /var/lock/LCK..modem
efax: 42:33 done, returning 2 (unrecoverable error)