It is normal to pass credit card information to Dell vendors via phone call?

I went to make a purchase at the outlet and asked for help on chat, through chat an employee offered me a discount to do direct sales with him, he sent me a quote by email, his email is from the user @dell.com with all contact transcribed via chat. But he asked me for my credit card details through a call to finalize the purchase, I was very uncomfortable passing my card details over the phone even to a Dell customer service representative, this is normal, it is really a legitimate process, I run the risk of falling for a scam?