I believe that you can. I changed my phone number two weeks after I got my Thunderbolt a year ago. I was able to view the details of the old number through MyVerizon account. It also made for an interesting bill to go through.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
How do you search for it though?
Like, the only line i see is my current number and i can't flip through the previous numbers and i need to find a number that i called from the previous number.
It was under the detailed usage I believe. I also remember looking at it after the bill for that month was generated.