I have a dual core machine with 1GB RAM. There are 8 to 12 SIP phones connected and logged in, and 4 FXO ports (digium card). When I get 1 call on the FXO the voice quality is OK. When I have 2 or 3 calls coming in the voice sometimes breaks up. All calls are recorded in wav format. When I do a top , the cpu load is 0.19 or less. However almost all my memory is being used (700MB out of 900 available) What can I do to improve the performance? Might disabling echo cancellation help? There are some other PCs on the network. Is it possible that they are slowing the network? I dont think this is a problem because the switch is good (Cisco).