We are having intermittent echo. Our setup is as follows: 3CX v10 latest Service Pack running as a VM under Windows Server 2008 R2. 4gB RAM and 2 processor cores allocated to VM. The server is a Dell Poweredge 2900 with RAID 10 drives. The desktop phones are Cisco SPA525G2 with firmware 7-4-9c. Our SIP trunk provider is Broadvox. Our broadband connection is Time Warner Business Class Road Runner [10mb down and 1mb up]. Broadvox has been testing on their end but no problems have been found. The network switch is managed and set to prioritize SIP traffic. Same for the router. I dont know what else to do to find out what is causing this? I wonder if this problem could be caused by latency on our internet connection? If so, would switching to a T1 connection be the solution? Any ideas would be appreciated.