I wasn't advised to use ubuntu, just including it as another data point (its my dev machine). I've tested against two physical servers. RedHat 6, Xeon 6 core 2.6ghz, 32g ram The dev machine running Ubuntu 13.04, decent Core i7, 12g ram I've tested on several XenServer instances running RedHat 6. All devises/hosts are on the same internal network. Seeing the same results regardless. The device on the other end of the calls is an external conference bridge (physical host). There could be some device specific issues - but I see the same results when testing against another freeswitch instance on the same network set up with mod_conference. Using g711 and recording to .wav. The call sounds unsatisfactory in real time and in the recordings Call quality is near perfect when the two calls aren't bridged into a freeswtich conference or our external conference bridge. But even setting up a basic freeswitch conference to run the tests against resulted in the lower quality. So "failure" case appears to be when two separately originated calls being bridged into any single conferenced environment. Just to be clear - the quality is ok, but not great. For reference, I'm expecting a PESQ score of 3.8 or greater - which is met with asterisk (seeing 3.8 - 4.3), but Freeswitch in its current setup consistently results in 0.5 - 1 point lower at around 2.9 - 3.7. I'm hoping there is some environment/configuration tweaking I can do to fix this. I have tried running FS with the -hp flag. Do I need to make configuration changes on my OS/network to account for that? Does this feel like an OS level issue? Do I need to try Debian 6? Thank you for the reply. Again, let me know what other info I can provide.