On Sun, Sep 24, 2006 at 01:58:21PM -0700, Christopher Corn wrote: > I've been reading about FOIP and there something i dont undrestand. maybe > someone can explain to me. > > A couple of faxing methods im confused about. > > The pass through method, sending fax data over G711 codec > versus > Relay method, t30 to t38 conversion > > > Can someone explain to me why the pass through method doesn't > require t30 to t38 conversion ( or does it do it?)? i believe > the conversion to t38 is so that it can be routed through a > packet network and then back to t30 so that the fax machine can > understand. why is it that if you use a pass through method, and > your still passing through a packet network, you dont need to > convert to t38 and t30?
I believe the proper answer to your question is this: Fax and modem tones will not be passed properly by some codecs because they're optimized for the frequency patterns of human voices -- and because those tones were themselves optimized for a traditional analog or DS-0 PCM channel. Since G.711 *is* an uncompressed DS-0, that's why you can pass fax tones through it, without any help from spoofing protocols like t.38. Cheers, -- jra -- Jay R. Ashworth [EMAIL PROTECTED] Designer Baylink RFC 2100 Ashworth & Associates The Things I Think '87 e24 St Petersburg FL USA http://baylink.pitas.com +1 727 647 1274 "That's women for you; you divorce them, and 10 years later, they stop having sex with you." -- Jennifer Crusie; _Fast_Women_ _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
