Why can't I port my number to a new cell phone carrier?

Michael has an old unlocked phone that he's trying to port to a new carrier, but it's not working. The company says it won't port an inactive number. Leo says the law requires porting numbers to his new service, but they could have found a loophole with an inactive phone. Leo also suggests doing a factory reset. That should clear out the carrier data. There's also something called APN settings which need to be cleared out so that the carrier can't reject it.