I expect Wes and Aaron will have useful opinions, but there might be other lurking Asterisk PBX users on the list. I'm close to finished configuring a small-but-complicated Asterisk setup for my wife's office - a few logic/dialplan/workflow tweaks remain.
The system connects three Cisco 7940/60g phones to three Centurylink POTs lines. I believe we are about three miles from the CO, but there is likely a nearby remote switch, because the fourth DSL/FAX line is running 7Mbps, and the loop must be short for that. We are in a commercial office building and don't get to tweak on the wiring onwards from jacks in the office. === The biggest remaining issue is echo. === 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 am running Asterisk 1.8.7.1 - pretty recent, but I am hoping to never update it unless a major flaw emerges. The analog FXO modules are chinaroby via ebay. I set /etc/dahdi/system.conf with echocanceller=mg2 on all the incoming analog lines. I set /etc/asterisk/chan_dahdi.conf with echocancel=yes echocancelwhenbridged=yes echotraining=128 rxgain=9.2 The rxgain was set by calling a 1004Hz 1mW test line in Seattle and calibrating with dahdi_monitor for a level of 14500 units. I couldn't find a closer test line, and the service techs at CenturyLink in Portland don't know what I'm talking about, but I assume that with digital trunks connecting these Centurylink COs I am getting the same level of signal. 9.2dB seems like a lot of receive gain, but it doesn't seem to affect the echo, and again, the folks at the other end hear us just fine. 99% of our calls are to the Portland/Vancouver area, we don't need three way calling, and we need to keep POTS/analog for reasons I won't dwell on here. If needs be, we can replace the Cisco phones, but I am not fond of "buy and try". Any suggestions? The woman answering the phones is ready to kill me, and she probably knows how to do that in a forensically undetectable way. I wouldn't want to subject her to the remorse, my wife to the burial expense, and you folks to the subsequent peaceful/boring mailing list. :-) Keith -- Keith Lofstrom [email protected] Voice (503)-520-1993 KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon" Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
