I prefer voice mail rather than the busy signal, but I let them know, I expect to hear from them and if they don't call back, I will assume that my business is not important to them and I will go elsewhere.
Don't like salescalls and automated calls.
I have this little device about the length of your index finger. As soon as I hear that it is a salescall, I push the little button and hang up. The sales person on the other end hears this message...."I'm sorry but this home does not accept calls of this nature, please take this as your notice to remove us from your mailing list....goodbye" and it hangs up.
Of course, recently I have come up with something called Privacy Manager. I never get sales calls anymore. It is great!