I'm not sure if it's the same way everywhere, but I did work at a telemarketer's for a bit, and I can share my experience.
It was at a point when I had been out of work long enough to be desperate for cash, and just happened to find out that this place was hiring. I've worked for call centers before, but never a telemarketing company. Still, I figured my call center experience might help me out.
Turns out I didn't really need it, because they didn't care. They put me in a room with other people and had us all read a pre-written sales pitch to see how we sounded while delivering it. I do theatre as a hobby so I have no problem working with something scripted. I got the job, as did a few of the other walk-ins, and reported for work the next day.
To say that working for a telemarketing company is awful, is an understatement. In this particular situation, we were all crammed into a "call center" that was really a hollowed-out office with desks sitting shoulder-to-shoulder. I sat at an old computer and was given a landline phone to work with. I mean something you might remember using from the 1980s, curly cord and all. Eventually I brought in my own receiver and headset (fortunately I already had these things buried in a closet somewhere and didn't have to buy them) just so I didn't have to keep trying to balance their phone on my shoulder so I could type and talk at the same time.
The company had contracts from different places. I remember Better Homes & Gardens magazines was one of them, as well as some company that sells packets for newborn babies to hospitals, and some surveys that had to be conducted. Each day we would come in and be told what contract we were assigned to, as well as how many sales were needed. If a person didn't make a certain amount of sales by a certain time of day, the company would let that person go for the day to save money. Happened to me at least once that I can remember, and it felt awful because it meant my meager paycheck would be even shorter.
There was no training involved. No sales techniques passed on by my team lead or fellow co-workers. The program on the computer would push a script or survey and dial a pre-programmed number. I had no control over what number was being dialed. I remember one day I was going through a list of magazine subscriptions and spoke to a woman who was interested, but needed me to call her back at a certain time. Perfect, I assured her I would do that. The program that pushed the script my way gave me the option to set the callback at a certain time/date. With that done, I kept going on with the list.
Once I got to the end of the list, the program rung the woman's number again. I didn't commit her number to memory because I expected to call her back later, but when she spoke I remembered her voice, and she even told me she "spoke to someone earlier and told them to call back later," clearly not remembering mine. I had set my callback for the next day, but obviously the program felt that since I had finished all the other callouts on my list, I should have given hers another try.
I also remember some of the times when people took great pleasure in being awful to me. A man who pretended to be interested, let me start in on my sales pitch, then hung up on me mid-sentence, was probably the lightest offense. I was more relieved to hear people tell me they weren't interested, rather than taking out their entire frustration with the concept of telemarketing on me as an individual.
Along with having to make sales, there was wording in the scripts that we had to use. Questions that had to be "checkmarked" before the call would be considered complete and not end up back in the system to be rung again later. I was always happy to do the surveys because most people didn't mind those, but the sales scripts, as you can imagine, had questions to check off that sounded repetitive and bothersome. You could put your own spin on them but the point was you had to go down the checklist, or that person was going to be put back in the queue to be called again by you or someone else on your contract.
It didn't take me long to be fired for lack of sales, and soon after I was able to get another job elsewhere. But the money from that telemarketing job helped keep me afloat for the period of time it took me to find something better. It also taught me what it's truly like in one of those places, and why it most certainly isn't the fault of the phone agent that you're being called several times a day about their sales pitch. I'm sure if that company had an automated call system that pushed calls at people, other places do as well. I also hope that what I've written here gives a little insight into what sort of negative conditions that person on the other end of the phone may already be under. I was out of work for a period of time, I was nearly out of money, and if not for the time I spent in that job, I might have been out of a few other things as well. I do not wish to repeat that experience, but having had it, I have learned to politely decline sales people no matter where and when we meet.