Hi, 

I've been testing Sipxecs (4.0.4) running on both Xen (plenty of resources) and 
a dual-PIII - 1.4 GHz with 4GB of RAM. Sipxecs turns out to be a great piece of 
software, and nearly ready for production use, except for one annoying problem: 
a clicking sound is audible on calls being bridged trough the ACD server. At 
first, i suspected the Xen virtualisation because of the well known timing 
issues with RTP so I did a fresh install on the P-III box only to find out the 
problem still exists! On calls bridged trough the ACD server, a clicking / 
chopping / rumbling noise is heard in the background when the other side is 
talking (when both ends of the line are silent, no clicking noise is heard). 
Voice is sometimes distorted as well. I played around with codecs, but nothing 
helps. I tried a downgrade to 4.0.2 but that didn't help either. 

The setup is as following: 

SipxECS (running in datacenter) <==> INTERNET <==> Phones (connected trough 
NAT, tested without NAT). 

Things I have excluded from the equation: 
- System load (the ACD calls are the only active calls, being the caller and 
the agent. CPU usage is around 3%). 
- Software version (problem exists with both 4.0.4 as with 4.0.2). 
- Virtualisation (sipxecs is now running on the physical hardware layer). 
- Bandwidth problems (plenty of bandwidth available, sipxecs box connected by 
100mbps to the Internet. Test phone, connected by 100mbps uplink as well) 

Things I haven't excluded: 
- Switch (both test machines are in the same cabinet, therefore using the same 
Netgear uplink switch). 
- Phones (test phones are Linksys SPA-941 and SPA-942) 

Does anyone have a clue, where to look for the cause of this problem? I cannot 
imagine anyone using the ACD in production use with such poor audio quality. I 
know the ACD has been subject of discussion for quite a long time, but for a 
small setup as I'm proposing right now I hope it is usable (no more than 5 
simultaneous calls, 4 agents). 

Thanks for any replies, 

Kind regards, 
Remco. 
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