What is this lead for on my car tracker?

My employer recently fitted a tracker on all of our company cars which is fine but I'm confused by a lead that appears from under my dashboard that looks like a telephone cable and I have been wondering what it's for but I keep forgetting to ask the transport guys who I don't see very often. At first I thought I could plug my Sat Nav into it but the lead is too big so if anyone knows that would be great!|||i think thats where they plug their lead in to oyur van to get the data off .