It is completely legal to track a stolen phone because you are the legal owner of the property. Using a service like Scannero to find the location is fine, and sharing that data with the police is exactly what you should do. If you want to try tracking it, this website can help pinpoint the device via SMS tracking. However, never try to confront the thief or retrieve the phone yourself, as that can get dangerous or legally complicated. Just pass the coordinates directly to local law enforcement and let them handle the recovery safely.