Prospects calling back

So I have a direct line at work that transfers to my cell because I'm based out of Vancouver, but the direct line is a San Fran number.

My question is this. When a prospect is calling you back, and the incoming number shows up as your office number, how do you find out who they are without insulting them?

Obvious answer is to quickly look up their name on your CRM if you are at your computer. But what if you have multiple prospects with that name?

I'm sure you could use the line: I'm so sorry but I'm not at my computer right now, could you refresh my memory. Who do you work for again?

How do you deal with not knowing who the prospect is when they return your calls?