On Thu, Jan 05, 2012 at 01:09:05PM -0800, Keith Lofstrom wrote: > The echo may be due to the Cisco handsets, which are functionally > opaque. The echo on at our end, which sounds like very ringy > sidetone listening on the handsets, ranges from briefly annoying > to completely unacceptable. There is no detectable echo on > either the voicemail or for those calling in. I'm guessing > there is some second echo cancellation process that I need > to turn off.
I assume you also don't get the echo when you do an echo test (*45). It's been a while, so I had to refer to Cisco's fine documentation: http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml http://www.cisco.com/en/US/products/sw/voicesw/ps1860/products_tech_note09186a00800b4a71.shtml#topicsub1 http://www.cisco.com/en/US/docs/ios/solutions_docs/voip_solutions/EA_ISD.html Sounds like "hybrid echo" - an impedence mismatch is causing an echo (or even oscillation) between the FXO on your end and the PSTN "hybrid". I understand you can use the "fxotune" util to autotune settings. Also check http://kb.digium.com/articles/Troubleshooting/General-Echo-HOWTO > The rxgain was set by calling a 1004Hz 1mW test line in Seattle > and calibrating with dahdi_monitor for a level of 14500 units. You used something like this procedure? http://www.mattgwatson.ca/2008/05/howto-tune-zaptel-dahdi-fxo-interfaces-on-asterisk-pbx/ I'm glad you're bringing this stuff up. I just got the go-ahead to bring my wife's business telephone system into the late 20th century. I'm thinking Norstar key system... _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
