I have to confess that in my younger days, I did work as a telemarketer very briefly. In spite of having a good phone voice, I wasn't very good at getting people to buy things that they didn't want to buy and so my career as a telemarketer was very short-lived. Even though I got paid per time I was able to finish my whole script, I was never pushy if someone said they weren't interested (probably part of the reason why I didn't last long in the job).
Where I work now, the telemarketers are relentless. Sometimes they will call EVERY DAY for a month at time and my boss doesn't want to talk to them so it's my job to screen them out and for the most part that's pretty easy because they either mispronounce his name or use the long form of his name when he uses the diminutive with anyone who knows him. But these folks can be VERY rude and I've had them cuss at me and really, if you want my boss to buy something from you and you cuss at me, it isn't going to happen. I don't care if you have a Platinum Deluxe Ball Buffer Pro that you're selling, if you cuss at me when I try to screen your call, your balls are going to be in the wringer, buddy.
The other thing that happens time and time again is that we get people who call for boss #1, make their pitch, get rejected, hang up and then seconds later, they call for boss # 2 and get rejected, hang up and then they want to talk to Office Manager... and yes, rejection AGAIN. One company has called twice a day each day this week and I try to be polite when they do this but eventually I get very firm with them, even when they don't want to hear it.
I can't believe that telemarketers actually sell enough to make their continued existence worthwhile, but apparently they do or I wouldn't have to put up with them calling the office every day. Some days I feel like answering the phone and saying "if you are selling something, we don't want it, please state your message at the tone and A GOOD DAY TO YOU!"