I'm thinking it's someone that might've bought it here, while on vacation... Did it appear on the newer side? Seems weird to have no sim... Sounds almost like they bought it without a sim from some shady place.. OR.. It's potentially someone elses phone that they have, and the sim was removed to prevent tracking... I wonder if it would still connect to wifi, and some sort of tracking might kick in... Apple ID, find my iphone or something... Cool of your GF's son to do the right thing!
I "lost" an iphone 4s recently, also known as 'drunkenly passed out in a limo during my friends bachelor party', and had the most annoying, trashy, taxing journey trying to get it back from the company. Let's just say it ended with me lying, and claiming I had tracked it to the limo place, the 'guy who cleans the limos' lying, and saying that he didn't have it. Only for me to 'lie' and say I was calling the cops.. In which time, his ex-gfs daughter stole it from him, and called my parents to say she had it. Then, as I'm waiting for her to call me back with an address for me to send a shipping label to, plus a little thank you - she calls me back frantic, at 2 am, saying that her moms ex came in, and stole the phone back from her, and threatened them.
So, I then have to call the cops, saying I don't know who these women are, but I think their lives are in danger. The cops then say I have to file a report online, because I am out of state or some bullcrap. that morning, I call the limo boss guy, and tell him that I am most certainly calling the cops, and filing a report, and I know he has it. He finally comes around after the second round of questioning. They send me my phone back, the jerk deleted all my photos/videos/etc from the phone already.. And, the limo place supposedly fires him. Yeah, that was fun. However, in the end, I got a replacement by the time the phone showed up, and sold the new one I got from insurance for a profit of $300... So, I win.