How to juggle multiple phone lines at once as a receptionist?

I've had 3+ years in a small office call center and I am thinking of moving into receptionist work. A call center deals with one customer at a time. Do receptionists deal with a lot of handling the customer service complaints via phone or are they mostly transferring calls to others? I just don't see how you can have a 4-6 line phone system with lines all on hold, trying to deal with solving an angry customer on one line, and then have to put them on hold to deal with the other lines and having to keep putting people on hold while dealing with more customers? What if they say no to being put on hold? Do you just ignore the other calls coming in while someone is angry? I guess I'm looking for a typical day and the protocol for answering multiple phones in a situation like this. It just seems weird for customer service to have to keep interrupting the solution process by putting them on hold cause other calls keep coming in, it would piss them off more.