Google Voice

There is a way to get two phone numbers on one cell phone: Google Voice.  This uses VOIP through the Google Voice app and will let you choose a second phone number for your phone.  I use mine for Android tech support for my customers.  If you want to distinguish between people calling your cell phone number and your GV number simply go into settings through the web application on your computer and select "display google voice number".  This way when someone calls it will show your GV number instead of the usual caller ID.