I use Click For A Call for all of our 800#'s to track all of our advertising sources. They have an awesome back-end tool where I can instantly add another number, change forwarding numbers, reports that you wouldn't believe so I can see when calls are coming and from what sources, during what time of the day, etc. They also have a great feature where I can have the call route to another number if the phone doesn't get answered. And of course you can listen to the calls.
I am in the process of switching over to their live chat as well. I have one ISM at each store using it and will add the rest of the ISM's soon. We don't get a ton of chats compared to visitors (like most websites) but the closing ratio is through the roof! My ISM's do the chat.
All of this wrapped together in one package is half the cost of what most 800# companies charge!