The most useful feature is the ability to see, hear, and speak with the person on the other end of the line. This is the only way to ensure that you are speaking to the correct person and not just hearing an automated system. I do not like that you cannot have more then one conversation at a time, and that you cannot have more than 1 conversation at a time. I would like to be able to speak to more than one person at a time. I have had a lot of success with Next Caller. I am able to help people who have been waiting on the other line for a very long time.