You will have 1 or 2 phone interviews and will been emailed a paper script if you've made it that far. Practice with someone as if they are a customer. Don't point out flaws in the script like grammar, morality etc. Be as aggressive and relentless as possible. Control the call, it "the customer" asks a question, answer it and then get control back again by asking your own question. They love saying, "it is easier to reign you back in than it is to toughen you up." Basically and sadly, if you feel like a jerk, you are doing it right.