asterisk users - Oct 2007 - Distributed FAX - How to best complement asterisk ?

Hi list,

  I'm evaluating a private telephony scenario of about 20
  locations - 300 phones, 50 FAX machines.

  Initial overview points to the installation of asterisk at three
  locations connected to the PSTN via ISDN PRI.

  All other locations, small by themselves, would get SIP
  phones managed by asterisk, since there is good IP
  connectivity between all sites.

  Now on to the subject... Handling FAXes:

  1. On the locations where asterisk is installed, the
      solution is "trivial"; either by connecting FAXes
      to FXS ports on channelbanks or by managing
      faxes with iaxmodem + Hylafax. Probably a
      combination of both...

  2. On the remaining locations "we have a problem"
      which I have been studying and trying to address...
      Faxing over IP.

  Side note:

  - I've read every recent mail on this mailing list regarding
    the subject
  - I've browsed the wiki to its fullest extent
  - I've googled a lot
  - I've read Steve Underwood's excelent summary on the
    subject (check it out at http://www.soft-switch.org/foip.html)

  Facts:

  a) FAX over VoIP will not work, so installing ATAs on
      the remote locations and bridging them with the PSTN
      FAXes is out of the plan.

  b) T.38 is the answer to FoIP

  c) asterisk 1.2 does not support T.38

  d) asterisk 1.4 only does T.38 passthrough, not good enough

  e) CallWeaver seems to support T.38 gatewaying, although I'd
      rather move on with asterisk so as to leverage current experience
      and knowledge and to keep installed base with the same software.

  Possible solutions point to complementing asterisk installations
  with T.38 capable equipment. (of course, one other solution
  would be to subscribe to analog lines at each location! however,
  this would prevent us from performing FAX CDR accounting --
  not a requirement, but a really nice-to-have).

  Having said all of this (and please correct me if I'm wrong) I'm
  looking for suggestions on how to best complement asterisk in
  such a scenario.

  The architecture I'm currently considering is:

  [PSTN] <---PRI---> [asterisk] <---PRI---> [PRI-to-T38 GW] ...
  ... <--SIP/T.38---> [T.38 ATA] <---FXS---> FAX machine

  On incoming faxes, asterisk would simply Dial() the PRI
  leading to the PRI-to-T.38 GW which would be configured,
  according to the dialed number, to connect via SIP/T.38 to
  the respective T.38 ATA.

  Outbound would have the PRI-to-T.38 GW work the other
  way around, calling asterisk with the PSTN FAX destination
  number... Again, asterisk would only have to Dial() out to
  the PSTN.

  My questions:

  1. What do you think of it, Is it feasible ? Does it make any
      sense ? How would you do it differently and why ?

  2. I believe a Cisco AS53xx + Cisco ATAs would do the job.
      What about a Patton SmartNode 4960 + Patton ATAs ?
      (I have very little knowledge about Cisco equipment, but
      I'm almost 100% sure the Ciscos would do it... on the
      other hand, I've read most of the Patton docs and, again,
      I'm also almost 100% sure these would do it -- however,
      hands on experience and knowledge counts a lot!)

  3. Roughly, how much would one expect to pay for one such
      PRI-to-T.38 gateway ? 5k, 10k, 20k ? Probably the Cisco
      version will be more expensive, no ?

  4. Of course, I could use CallWeaver as a PRI-to-T.38 gateway...
      But then again, how solid would it be ? With which ATAs ?
      The CallWeaver website shows a very small amount of ATAs
      confirmed to be 100% working in T.38.

  5. Would I need to have a SIP proxy between the PRI-to-T.38
      gw and the T.38 ATAs or would they be able to talk to
      each other directly ? (I'd say this would depend on the
      specific equipment, but...) If that would be a requirement,
      which way would you go, asterisk 1.4 ? Would SER forward
      T.38 traffic ?


  Thanks for inputs and experiences in complementing asterisk
  with T.38 equipment.
--
  exvito

Ex Vito wrote:
>   2. On the remaining locations "we have a problem"
>       which I have been studying and trying to address...
>       Faxing over IP.
>   
Could the 'remote' locations make do without a fax machine proper?  We 
have sheet-fed pdf scanners here, drop the document in and hit the 
button, and acrobat shows up; hit print, select the printer called 
"Fax", hit OK, and type in a phone number.  Done.  The last bit (the 
fake printer) is installed by "WinPrintHylaFax" [1] which is a windows
client that sends jobs over IP to a hylafax server.    I'm not sure how 
attached to a manual fax machine your users are, but mine sure were, and 
this sheet-fed pdf scanner combined with winprinthylafax appeased them.

Moj


[1] http://winprinthylafax.sourceforge.net/

On 10/10/07, Ex Vito <ex.vitorino at gmail.com>
wrote:
>   Hi list,
>
>   I'm evaluating a private telephony scenario of about 20
>   locations - 300 phones, 50 FAX machines.
More than 1 PRI?
>   All other locations, small by themselves, would get SIP
>   phones managed by asterisk, since there is good IP
>   connectivity between all sites.
Private network? How good? How saturated? Could be possible to just
run ulaw if the quality is as good as your LAN
>   1. On the locations where asterisk is installed, the
>       solution is "trivial"; either by connecting FAXes
>       to FXS ports on channelbanks or by managing
>       faxes with iaxmodem + Hylafax. Probably a
>       combination of both...
Why channel banks?
>   2. On the remaining locations "we have a problem"
>   b) T.38 is the answer to FoIP
>
>   c) asterisk 1.2 does not support T.38
>
>   d) asterisk 1.4 only does T.38 passthrough, not good enough
Use a VoIP provider with t.38 for your faxes... easy solution.
>   e) CallWeaver seems to support T.38 gatewaying, although I'd
>       rather move on with asterisk so as to leverage current experience
>       and knowledge and to keep installed base with the same software.
I've been waiting for callwaver 1.2 final for a while. Tried some
betas and T38 gateway didnt work even when we put a Sangoma card in
the machine. Problem was on the SIP side.
>   [PSTN] <---PRI---> [asterisk] <---PRI---> [PRI-to-T38 GW] ...
>   ... <--SIP/T.38---> [T.38 ATA] <---FXS---> FAX machine
Too many PRI... Try:

PSTN <---PRI----> AS5300 <------SIP-----> Asterisk 1.2
PSTN <---PRI----> AS5300 <------SIP-----> Asterisk 1.4
<-----SIP----> T.38 ATA
PSTN <---PRI----> AS5300 <------SIP-----> T.38 ATA


>   4. Of course, I could use CallWeaver as a PRI-to-T.38 gateway...
>       But then again, how solid would it be ? With which ATAs ?
>       The CallWeaver website shows a very small amount of ATAs
>       confirmed to be 100% working in T.38.
There's a reason why CallWeaver is beta. As much as I'd love to
support their stuff. It's still in beta.
>   5. Would I need to have a SIP proxy between the PRI-to-T.38
>       gw and the T.38 ATAs or would they be able to talk to
>       each other directly ? (I'd say this would depend on the
>       specific equipment, but...) If that would be a requirement,
>       which way would you go, asterisk 1.4 ? Would SER forward
>       T.38 traffic ?
SER is a SIP proxy. T.38 is irrelevant to it. I'd use 1.4, your setup
seems pretty straightforward. You don't have a diverse population of
SIP phones and locations to manage.

Hi!
>   2. On the remaining locations "we have a problem"
>       which I have been studying and trying to address...
>       Faxing over IP.
There might be yet another option for you to consider: 

Some of the bigger MFC printer/copy/fax combo devices by Brother (and 
maybe also other vendors?) provide a fax-via-smtp feature and can built 
fax networks that way. I haven't tested that yet myself, but it might be 
worth a look given the fact that T.38 can't really be said to be a
"rock
solid" solution.

But then: Are you sure you want to rely 100% on IP only in your satellite 
offices? It might be wise to have 1 (analog?) line installed anyway.

Cheers, Philipp