This is a very touchy subject for me as I've been an active participant of the telemarketing world since the 90's. It seems to be the perfect part-time job for me.
One thing to remember is your DELIVERANCE. Your deliverance makes all the difference as to whether the call is going to go somewhere positive or straight down the drain.
Telemarketing for your own business can be a great experience and a fabulous way to really exercise how you present yourself, company and your services.
It's not an easy job I will say and it's very challenging. You have to learn to catch the caller at the very beginning of the call (probably within the first 20 seconds or so) and never be pushy. If you should happened to catch someone at a bad time, don't take it as a brush off, end the call with something like, "OK, we'll be in touch at a later date" or if you can get them to set a date and a time that's even better, at that point you'll follow up accordingly. (Just a little advice, just in case you decide to try it).
I believe you'll be amazed at the results you'll get.
For my offline marketing this is going to be my very first approach to a PC, and if I have no luck here, then I will spend money and follow up with a letter etc.
P.S. Telemarketing is not for everyone, you have to be really thick skinned and learn not to take insults and disturbing comments personally. For every rejection I feel there are two acceptances ...... and my goal is to find them.
Hope this helps a little.