In my last post I talked about how I got the Openvox A800P card. I found that the card was sharing an interrupt with one of the SATA controllers in the machine. The card would work fine, until the disks on that controller were accessed. So I ended up pulling the card and moving it to a new slot so that it did not share an interrupt. This helped with the majority of the clicking I was getting on the card. But I still had some problems with echoing when I talked on the line. The echo problem was solved by running 'fxotune'. After running this tool the audio quality really improved.
I still get a few clicks every now and then, that I believe are related to the PCI bus. I talked to the Openvox support people and they recommend trying a new motherboard. This is not something I have handy at the moment, so I'll wait on that. I do think that going to pure VoIP phones will help with some of the noise. The VoIP adapter I bought has some of the clearest calls.
Being able to tweak the Asterisk dial plans has really been interesting. It is actually a little trickier that I expected, but once you get the concepts down it becomes a little clearer how to really make it work smoothly.