Round trip or latency issues mean that is taking too long to communicate back and forth from the VoIP devices to the VoIP server.  If data packets arrive too late, then they may end up being discarded and create gaps in the audio stream.

FracTEL uses a variety of national servers, so if you are experiencing latency accessing a VoIP server then you have to contact your ISP to check your network connection.  

It is also possible that your communications path is using too many hops to get from point A to point B.  Network tools like trace route can help identify problems, but ultimately the ISP may not be delivering an optimal service.