Google Voice allows someone to pick and choose a phone number, from anywhere they desire and have that number show up on caller ID. So say you have a call come in from Louisiana that person may really be in Florida.
If you suspect this and have an open case, here is info on how to validate the number:
Since Google Voice numbers aren't listed in phone books or connected to physical addresses, they're difficult to trace. When you call contacts from your Google Voice number, it shows up on their caller ID, but standard phone traces don't reveal your identity. If law enforcement agencies become involved, Google provides them with your account information, including the IP address from which you created the account and placed calls.