Is it possible to lock the keys inside of a 2007 Prius?

All Corollas, Camrys, RAV4 ..Tundra...all Toyotas in the 2003 to 2010 time frame is it not possible to lock your keys in the car. If the drivers seat is unoccupied the locks will not engage. It is the same thing as wanting to lock your car and warm it up before you get in...no can do.

Can a cell phone interrupt the signal from the key fob to the system? For example, if the key fob was in the cup holder of the car and a cell phone was placed over it could it be possible for the fob to lose it's signal and therefore not work?

yes this is exactly what happened to my car I get so upset when fellow prius owners say it's impossible it is not!

The CAN bus has a few dead spots. If your smart key is in one of those spots, then the car won't see that the key is inside and and allow the car to be locked. Unfortunately, one of these spots is the middle of the passenger seat base. Best practice is to get a spare mechanical key (not that expensive) so that you can always get the door open.