[JQuill]

You could also be a victim of ESN cloning and someone is using your ESN to send out texts on another phone. Long shot, but make sure you check your bill and when you call they can tell you exactly what time they were sent and to what number, even if you haven't gotten your bill yet. I've never had any experience as a victim or participant in ESN cloning, but somebody can take the ESN off your phone and assign it to another device by hacking it, and both phones can allegedly be used at the same time, so even if you're using your phone as normal and it's powered on and in use, they can still send texts from another phone using your ESN.