[Freeswitch-users] Bad connection diagnostics?

Hi, I have a client who has been working fine for months, but as of late they are reporting connections where the audio only works in one direction or neither and "terrible echo". I know they had some issues with their local Cable Connection, but they are supposedly resolved. Results from "ping -n 50 -l 256 " and "tracert" are virtually identical to mine from here and I have no issues. Are there some diagnostics I could run to try and pin this down. The phones are all cisco 504Gs, the server is a VPS from synapseglobal. Thanks for any ideas you may have. Sean