If it's an Android phone you can try installing an app remotely from your PC to by our phone called "Plan B" and locate the phone through GPS on a Map. Just Google Plan B mobile and you'll find all the info.
I leave the WiFi and data off so plan b can't work? I suspended the phone but had been hoping to at least find out if someone found it.. it is locked so they would have to figure out or bypass that. So if someone finds and keeps it they just take out and replace the SIM card? Why can't they Havre serial numbers so of it is stolen they can't switch service without permission? O.o seems simple enough..