asterisk users - Jun 2016 - Problem sending and receiving faxes

Hi list!

I installed Hylafax on a Ubuntu-Server 14.04.
On this server runs Asterisk 11.7.0, too and it was configured like my own
Asterisk server at home, but it does not work... :(

So, I configured Asterisk to connect to Deutsche Telekom and it does!
Then I configured iaxmodem to speak with the Asterisk and it does, too.

But when I try to send or receive a Fax, it does NOT...
I always get "no carrier detected" (if sending) or "Ring detected
without
successful handshake" (if receiving).

In Asterisk debug modus I can see (sending!):

    -- Accepting AUTHENTICATED call from 192.168.60.1:
    --        > requested format = alaw,
    --        > requested prefs = (),
    --        > actual format = alaw,
    --        > host prefs = (alaw),
    --        > priority = mine
    -- Executing [03511111111 at fax-out:1] NoOp("IAX2/75-1749",
"") in new stack
    -- Executing [03511111111 at fax-out:2] Verbose("IAX2/75-1749",
"2,Call from FAX") in new stack
  == Call from FAX
    -- Executing [03511111111 at fax-out:3] Dial("IAX2/75-1749",
"SIP/pbxfax/03511111111,,R") in new stack
  == Using SIP RTP CoS mark 5
    -- Called SIP/pbxfax/03511111111
    -- SIP/pbxfax-0000006c is ringing
    -- SIP/pbxfax-0000006c answered IAX2/75-1749
       > 0x7faccc01e9c0 -- Probation passed - setting RTP source address to
217.0.4.71:27952
  == Spawn extension (fax-out, 03511111111, 3) exited non-zero on
'IAX2/75-1749'
    -- Hungup 'IAX2/75-1749'

and receiving:

  == Using SIP RTP CoS mark 5
    -- Executing [75 at fax_incoming:1] Verbose("SIP/pbxfax-0000006d",
"2,Internal Fax") in new stack
  == Internal Fax
    -- Executing [75 at fax_incoming:2] Dial("SIP/pbxfax-0000006d",
"IAX2/75,20,RxX") in new stack
    -- Called IAX2/75
    -- Call accepted by 192.168.60.1 (format alaw)
    -- Format for call is (alaw)
    -- IAX2/75-3054 is ringing
    -- IAX2/75-3054 answered SIP/pbxfax-0000006d
       > 0x7fad440366b0 -- Probation passed - setting RTP source address to
217.0.5.103:44706
  == Redirecting 'SIP/pbxfax-0000006d' to fax extension due to CNG
detection
    -- Hungup 'IAX2/75-3054'
  == Spawn extension (fax_incoming, fax, 1) exited non-zero on
'SIP/pbxfax-0000006d'
    -- Executing [fax at fax_incoming:1]
Verbose("SIP/pbxfax-0000006d", "2,Call for FAX -
[+493511111111]") in new stack
  == Call for FAX - [+493511111111]
    -- Executing [fax at fax_incoming:2] Dial("SIP/pbxfax-0000006d",
"IAX2/75") in new stack
    -- Called IAX2/75
    -- Hungup 'IAX2/75-10508'
  == Everyone is busy/congested at this time (1:0/0/1)
    -- Auto fallthrough, channel 'SIP/pbxfax-0000006d' status is
'CHANUNAVAIL'

can someone help me?

Thanks a lot!
Luca Bertoncello
(lucabert at lucabert.de)