URGENT: Need to track a lost mobile (Bangkok)

Hi folks, I need some urgent help. I forgot my mobile phone in the taxi on the way to the airport this morning, and although the airlines staff tried calling on the number, no one picked up despite the phone ringing. And now, Protected content later, the number is not even ringing but goes to an answering machine. Does anyone have any idea how I can try and track the phone (it was either a green-yello or orange taxi I think but I have no other details).
I am not even in Thailand now but need to try and track the phone - any advice?
Thanks in advance.
DN