What is the functional capacity of astGUIclient and VICIDIAL?
As with everything in Asterisk, this depends greatly upon how you are using the suite. Using only astGUIclients in a corporate environment with telco T1 lines, we have had over 60 concurrent clients operating on a single server with a max of 48 Zap -> SIP conversations on a P4 3.4GHz server. For VICIDIAL, we have had upto 40 agents running on a single server with the dial_level set to 1.3 or lower. And with the dial level set to 3.0, we have seen a ceiling of about 20 agents before funny things started to happen. We have tried Channel Banks to see if they help on loaded systems, and they do greatly reduce and eliminate the SIP buffer and echo problems we have. This does limit you to 24 agent channels, but the system does run better. Also, switching to Sangoma Quad T1 cards or 2nd generation Digium cards gave us a minimum of a 30% performance boost over older Digium cards. Quad T1 cards with hardware echo cancellation also raises capacity on these machines.
