Lost Iphone

Hi

I lost my phone yesterday and used the Find My App to track it. I put on the emergency lock and left a message for someone to return it. However on the Find My App from my tablet, my phone is appearing offline, but when my girlfriend called my number numerous times, the phone was ringing meaning it was charged and not turned off or dead. I also played the sound to see if I would hear anything and I didn’t, but every time I played it the play sound kept turning off consistently, my question is does someone else have my phone and if so is there a way you can help me get it or track the phone directly? thanks.