How to use 2 phone numbers on a cell phone?

[Julie Groth]

Ok, I know how to get a 2nd phone # (Google, others). I want to use the 2nd number on marketing materials. My 1st phone is my personal one, of course. Here's what I figured out so far:

1. People can call the 2nd number and listen to my recorded voice message. If they leave a message, then an email is sent to me with that recording.

What I don't know how to do:

(1) when I return the call, I want them to see the 2nd phone number as the one that shows up on their caller id? 

(2) how can I switch it so that I can answer the phone, if I want to?

What do you all do?

Thanks! Julie