| It happened to me also. a month ago (for the first time and in a taxi)
You should call your company to cut your actual SIM so if someaone want to use it to call, it wont be possible. And buy a new one, your company should send you a new SIM within 1 week tops.
Good shopping for the new one !
nb: If it's a hongkongese who found your phone, don't worry, he/she wont try to use it but if it's a foreigner, you can bet that he/she will try to call his home country with it so cut it now ! That's what I was told ! | 
