I received a call this morning from the 480-713-5000 number. They said they were Vanguard, and they knew my name and asked to answer a security question before proceeding. I explained that I was uncomfortable doing that and asked if I could call them back so I knew who I was talking to. They said I could use the number on the Vanguard website, but also gave me 800-823-7413
. I chose to use the number on the company's website instead, and when I called, they did confirm the note the other person had mentioned writing. So apparently the call was legit, but it never hurts to be careful with these things!