tritch-Agree that the problem most likely upstream congestion. The Grandstream and the OBi110 were setup in the DMZ on the router there for by passing the firewall etc. VOIPO set it up. I was having problems today in the morning. Interesting though, I had T-Mobile voip for years and no issues.Could be the router not sure what more I can do. QoS is also setup giving highest priority to the LAN port the ATA is attached too. Problem is intermittent.