I am having trouble with call choppiness on the called number's end of the connection.

This does not happen all the time. 30-40%

I have set up Qos, Port Forwarding, etc even bumped up my internet down load and upload speed to help. No improvement.
I tested with Google Voice and Magic Jack and this does not occur.

I have a "A" rated signal at Ping.com and still having problems.

Is there a set up access in the Grandstream router that can possibly help?

I am a new customer and the service is great except for this annoyance.