asterisk users - Aug 2004 - is asterisk and/or spandsp what I need for integration with Cisco?

Hello list.

I've been running a Cisco VOIP WAN for the last two years using CallManager
V3.2.  The remote 1760 routers are set up as H323 gateways.  I've got a
VG200 that is my PSTN gateway with a full T1 voice trunk to the local CO. 
I'm also running Unity v3.x for voicemail.

We are currently using two ATA186 devices that are using the G.711 codec to pass
incoming calls on the T1 trunk to fax machines in 2 separate buildings.  The
other fax machines in our buildings are simply connected to POTS lines.

I'd like to get rid of the POTS lines and consolidate all of our fax
machines using a fax server.  I've been successful in hooking up the ATA186
device to an external modem that is connected to a hylafax server.  What I'd
really like is to do away with the ATA devices and modem.  The hylafax server is
already on the VOIP network, so I'd really like some solution that
doesn't require converting the call back into a POTS line before I can
handle it.

Will spandsp work for this?  Do I need asterisk as well?  I can get a call to
the hylafax server using the G.711 codec.  I'm not sure if I'd still
need some sort of hardware to use spandsp.  I tried using T38Modem, and it would
work up until it tried to switch to fax mode for the H323 call.  So I found out
that CallManager can't handle t38 (and neither does my vg200) and my
attempts to get a Cisco 3640 to act as an H323 to H323 w/t38 gateway have been
unsuccessful.

If spandsp doesn't work, is there any other way I can use asterisk?  The
only other solutions I can come up with involve doing loopbacks between fxo
ports or using the ata devices as some sort of intermediate link.  Either way
it's a kludge.

Brian Jarrett
Network Administrator
Garfield County School District 16

On 2004.08.05 15:01 Brian Jarrett wrote:
> I'd like to get rid of the POTS lines and consolidate all of our fax
> machines using a fax server.  I've been successful in hooking up the
> ATA186 device to an external modem that is connected to a hylafax
> server.  What I'd really like is to do away with the ATA devices and
> modem.  The hylafax server is already on the VOIP network, so I'd
> really like some solution that doesn't require converting the call
> back into a POTS line before I can handle it.
Unless you are using ISDN or have some way to get t38modem to work with 
your VoIP gateways (as you mention H323), then currently this is how 
you have to configure Asterisk and HylaFAX to play together: in the FXO 
port to Asterisk out an FXS port (in your case an ATA device) to the 
HylaFAX modem.  Yes, it would be nice to eliminate the FXS port and the 
modem.  (It would also make the communication more reliable.)
> Will spandsp work for this?
I can't speak for him, but I believe that Steve Underwood (spandsp 
author) is working on a pseudo modem for HylaFAX to use which will 
allow it to work with spandsp and Asterisk without the additional FXS 
port and the modem.  Search the -dev archives for details.
> Do I need asterisk as well?
Well, in theory you could use any PBX/VoIP gateway that will allow you 
to accomplish what you need, but yes, we generally talk about Asterisk 
solutions here.

Lee.