On Tue, Mar 16, 2004 at 02:16:01PM -0600, Jim Sneeringer wrote: > > Why does Asterisk not work as well with fax modems as any other phone > system? >
Because Asterisk does TDM in software. It's handled by 64 bits chunks, instead of bit by bit on TDM hardware. It has two consequences : - if for some reason (timing, load, bad luck...) a chunk is lost, you loose 1 ms of sound. This matters for modems. - handling sound 1ms at a time induces some slight delay (>1ms), but which can easily produce echo on analog loops (you don't hear it when it's 1/8000th of a second later, but if can matter if it comes back a few ms later). Thus Asterisk uses echo cancellation, which may alter data transmission. Hopefully tone detection deactivates it though. -- Nicolas Bougues Axialys Interactive _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
