Your cell phone company can tell you where the phone was at the time the guy answered. The sooner we all know that, the better idea we will have where to look. If the thief is stupid enough to leave it on, maybe your cell phone company can help you locate it. It is YOUR phone YOU are asking about, they should be able to tell you without citing privacy or legal concerns.
Also...
Does the van have a Qualcomm unit on it that will make it more distinguisable from other vans?
If it has a Qualcomm unit, can your carrier help you locate the van?
What about transponders like EZ-Pass or I-Pass?
Does the van have windows in the back doors or sides?
Diane is driving our truck at the moment and is looking over every white van she sees. The more detail you can provide, the easier your van will be to spot among all the others. They do not all look alike.