All you can do is test it first. I have been asked to do it for clients who have PSTN gateways that don't support t.38 and it has worked surprisingly well. Let me qualify that though by stating that the senders analog fax machine is directly attached to the analog or ISDN pstn, and has a telco tdm connection to a decent PSTN gateway that converts to G711. The G711 then goes across the wider internet and is terminated by txfax running Callweaver or Asterisk. Provided jitter is low, I have been extremely surprised to see this scenario work reliably between Europe and Australia (about 300ms latency). I have seen t.38 fail in testing at the 385ms mark, although this may be probably dependent upon the negotiated payload and buffer size.
I will be testing a similar scenario in a month or two using level3 as the inbound DID provider and hosting the rxfax either directly on the level3 network, or on a network with a private layer 2 cross-connect (MPLS or ethernet), I would not be surprised to see it as good as TDM. Where you will have problems will be cases where Joe small business at home has his fax connected to some cheap-ass ATA in turn going across his ISP's public internet connection to a VoIP provider that in turn relays to someone elses media server, the packets get bounced around various parts of the internt a few times, competing with bit torrent traffic and then end up on someones LCR'd PSTN gateway that makes a long distance 2nd or 3rd class TDM call to the PSTN destination. Craig -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve Underwood Sent: Wednesday, 30 May 2007 10:46 PM To: Users Mailing List - Non-Commercial Discussion Subject: Re: [Callweaver-users] TxFax/RxFax over G711 Roy Sigurd Karlsbakk wrote: > > Den 28.5.2007 kl. 16:47 skrev Eugene Prokopiev: > >> Hi, >> >> Is it possible to use TxFax/RxFax to send/receive faxes over voice >> instead of T.38? > > Given a low-latency link with low or non-existent packet loss, no > jitter, sunshine and some good bordeaux wine, yes. And terminal equipment that won't screw up the signal. Many will, and will *never* pass a FAX, despite their menu's having special FAX modes. And the clocks can't be too far apart. And the wind must be in the right direction. But, hey, sometimes it works perfectly. :-) Steve _______________________________________________ Callweaver-users mailing list [email protected] http://lists.callweaver.org/mailman/listinfo/callweaver-users _______________________________________________ Callweaver-users mailing list [email protected] http://lists.callweaver.org/mailman/listinfo/callweaver-users
