He said there were "milliseconds" between pushing the send button and it being received.
"Unless they are not in a coverage area. That's probably going to be one of the issues here, whether the CBD of Masterton is within the network coverage," Mr Wilson said.
Rose was driving the car 16-year-old Tegan Moyes was thrown from after it rolled on the southern approach to the Opaki overbridge, on February 21.
Miss Moyes received head and spinal injuries and was flown to Wellington Hospital, where she died of her injuries.
Judge Bill Hastings adjourned the hearing for mobile company 2degrees to supply information about coverage and timing.
The hearing will proceed on October 18.