VOIP Issues

We just got a web based VOIP system within the last year. We have been having internet issues ever since. Here are a few questions I have.

Should we have seperate data line for Phones?

Can anyone recommend a good router?

we are a small company with less than 20 employees. We are currently using a linus two wan router that keeps crapping out. It is the VOIP router the provider recommended. We are using Linus RV016 router.