What happens when you try to call your phone?
I lost my iphone............thrice. Ashamed to say it, but all three times when i was out drinking (surprise surprise). First and second time, I apparently dropped it on a bus but kept calling and calling and finally the bus drivers answered and I was able to meet up with him to get my phone back. In both cases i gave the driver $50. Figured it was a small price to pay.
Third time, left it behind at the bar. Luckily I knew the bartenders well and no one swiped the phone off the bar where I left it, so the bartenders had it when i called the bar up the next day. I tip very well when i'm at the bar so in this case i didn't feel a need to reward them. Considering that's what I expect bartenders to do when customers leave stuff behind.
And this was all in NYC!!! So I don't ever want anyone to say new yorkers are "bad"
Guess it's good karma considering i once found a cell phone in the back seat of a nyc cab really late at night, turned it off to preserve battery then turned it on the next day and called the owner and told the owner i found his phone in the cab and he could drop by my office to get it back. He was one happy guy.
But i totally feel for you, all three times i was going out of my mind the next morning, not from the hangover but from trying to track down my iphone. Best thing to do is just keep calling the number. Be persistent. Also, send a text message to your iphone, through email to sms text or from your friends phone. Since that will pop up on the lock screen, start off with "This is the phone's owner" or something along those lines, and let the finder know that you will provide some kind of monetary reward in the text message and leave contact info. I also wouldn't make any threats of police or such. Just be positive about it. If you are unlucky and a real jerk got your phone, no threat will make him go out of his way to return it. Also, leave voice mail messages. In general, if someone does have the phone, you probably will get it back. Most of us have lost a phone once or twice and can relate to your situation and the finder will generally be sympathetic.
Good luck!!!