Hello. My name is Michael. I can help you with your question.
They DO have the ability to triangulate the position based on cell towers. At least it is technically possible. I don't know what you would need to do it however - possibly a court order. It believe it would go through the local police station. Since it's used both in criminal cases and search and rescue. It is an alternative to GPS that will work as long as the transponder is turned on.
Verizon could but they have no way to do it (of which I am aware) or they cannot do it without a court order. That's why I suggest going to the police department. They have the capability to do this to find criminals and missing persons. Time is of the essence. Go to the police department.