On Wed, Nov 01, 2006 at 08:29:32PM +0200, Tzafrir Cohen wrote: > On Wed, Nov 01, 2006 at 09:08:43AM -0600, Ejay Hire wrote: > > This is incorrect. The data is still packetized and passed through IP which > > provides the same echo cancellation and distortion issues as a call that > > passed through an FXO/FXS card. > > The issue here is an "implementation bug" of Zaptel rather than a > fundemental archtectual flaw. > > For fax or modem to work well you need a good line. One of the problems > that may cause line quality problems is different clock speeds of > different components of the system. They may cause an occasional "click" > every number of seconds.
The jargon is "clock slip", and it happens when you don't have your T-1 clocking master/slave hierarchy set up correctly -- or when you have drops from two different switches from two different carriers (local and LD spans, for example). > The problem I referred to is that different Zaptel cards may have a > different clock. Asterisk uses the clock of the "master" zaptel device, > but it is not exactly clear who that master device is (basically: the > first Zaptel device). No other device tries to get clocking from it. > > If you use an external channel bank you work around the problem by > connecting all the external connections (both PRI lines and channel bank > FXO/FXS lines) through the same PRI card. That card will not have a > problem being in sync with itself. > > As for our device: our short-term solution is to sync the PC clock from > Zaptel as we can already sync our device from the PC. But the long term > solution is to sync our device (and other zaptel devices) from the > master zaptel device. Well, optimally, every T-1 card should be slaved to it's span, and buffering should take care of keeping various spans in sync with each other. 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
