Who else here needs to answer phones as part of their career? I'm a banker, and we get lots of calls every day about peoples' accounts. In other jobs I've also answered phones. And I feel like this needs to be said!
Things to keep in mind when speaking on the phone:
1. The person you're talking to is a human being, just like you. They could be your sister, friend, mom, brother. We're not robots. We have feelings, too. Treat us with the respect you'd want if you were in our shoes.
2. We're just trying to do our jobs, and pay our bills. We're not trying to make your life more difficult, we promise. We don't come to YOUR job and swear and scream at you, so why would you think it's an acceptable thing to do? If we give you an answer you don't like, it's not because we're trying to be jerks. It's a policy, or rule, or what our supervisor tells us.
3. On a related to #2 note, if you're not happy with what we're telling you, you CAN calmly as for our superior. You don't have to be nasty about it. I understand you might want to speak with someone who has more authority to make more decisions. I'm ok with it if you want to go up higher in the chain then me. Instead of yelling and hollering that I can't do what you want, let me transfer you to someone who CAN help you.
4. If you're nasty, and swearing, and being completely uncivil, I will NOT want to help you more. If you're nice, and calm, and reasonable, guess what? I'll be 100x more likely to work extra-hard to help you. I'll go the extra mile for anyone who is nice to me. Kindness is a 2 way street!
5. Believe it or not, I do actually want to help you and solve your problem. I don't want to say "no". Saying "no" makes MY job harder. But if you make completely unreasonable and outlandish requests, I can't work with you. Try and meet me with halfway, listen to my suggestions and try and see things from my perspective. Work with me, I can't help you if you're not willing to cooperate.
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I just needed to vent. I don't get people that think that since they're not talking to the person face to face, they can treat the person on the phone like garbage. Have some manners, for goodness sake!

"Avoid loud and aggressive persons, they are vexations to the spirit." - Desiderata, Max Ehrman.
1926.