So far, I have 3 remote sites on DSL connections, each using 3cx proxy to connect to the 3cx server site. At the 3cx server site, I have a patton 4114 with PSTN connected.
Everything works at a basic infrastructure level, but there are some voice quality issues. For the most part, extension to extension calls between the remote sites and from remote site to the 3cx server site are fine.
The problem seems to be when PSTN is involved. If a remote site 3cx extension places an external call, the 3cx extension end can hear the external party perfectly, but the external party cannot hear the 3cx extension end very well. The audio is very choppy. When an external caller places a call to a 3cx remote extension, same problem. Calls from the main 3cx site placed to external numbers don't seem to be a problem.
This is telling somebody something, but I don't know what ;-).
The topology is a bit more complicated thatn it should be - I could see what can be done to simplify it if that might make a difference:
Remote Extension > 3xc proxy > ISP provided xDSL device (router, DHCP, switch) > (internet) > fixed IP on cable modem > main site router (fortigate) > switch > WS2k8 R2 host > 3cx v10 running on WS2k8 R2 Hyper-v child. The Patton 4114 is connected at the switch, along side the 3cx server.
The extensions are Grandstream GXP285 and 1200, as well as 3cx Phone v6.
If anyone has some ideas to put me on track to troubleshoot the voice quality issues, I am grateful. I'm not really sure where to start.
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