Hylafax on virtualserial COM on KVM

Hello guys,

first of all sorry for my english!!

Well, I have a problem with my fax server (CentOS 5.8) virtualized on a KVM
server (CentOS 7). 

Everything's ok but, for my fax server I connect a analog modem (digicom
Botticelli) on serial com virtualized by qemu/libvrt (/dev/ttyS1).

I use Hylafax 6.0.6, I receive fax without problem, but when I try to send a
fax I receive always this error message:

ERR [333] Failure to transmit clean ECM image data.; too many attempts to
dial

this is my configuration script fo COM port:

</serial>

    <serial type='dev'>

      <source path='/dev/ttyUSB0'/>

      <target port='1'/>

    </serial>

 

Somebody can help me?

Thanks in advance!!