What internet phone service allows the most conference call minutes?

I want to know which service allows me to LISTEN, not host, to the most conference calls, i require around 1000 minutes a month.

and let me know the price & quality, i.e. is there an echo?

With "Skype Unlimited USA and Canada", you will get unlimited conference calling for $3/month. Skype allows you to conference up to 10 people.

Skype has recently upgraded their softphone to version 3.8, and the call quality is better than ever.

Skype pro is $3 a month.